linux/mm/page_table_check.c

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mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2021, Google LLC.
* Pasha Tatashin <pasha.tatashin@soleen.com>
*/
#include <linux/kstrtox.h>
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#include <linux/mm.h>
#include <linux/page_table_check.h>
mm/page_table_check: support userfault wr-protect entries Allow page_table_check hooks to check over userfaultfd wr-protect criteria upon pgtable updates. The rule is no co-existance allowed for any writable flag against userfault wr-protect flag. This should be better than c2da319c2e, where we used to only sanitize such issues during a pgtable walk, but when hitting such issue we don't have a good chance to know where does that writable bit came from [1], so that even the pgtable walk exposes a kernel bug (which is still helpful on triaging) but not easy to track and debug. Now we switch to track the source. It's much easier too with the recent introduction of page table check. There are some limitations with using the page table check here for userfaultfd wr-protect purpose: - It is only enabled with explicit enablement of page table check configs and/or boot parameters, but should be good enough to track at least syzbot issues, as syzbot should enable PAGE_TABLE_CHECK[_ENFORCED] for x86 [1]. We used to have DEBUG_VM but it's now off for most distros, while distros also normally not enable PAGE_TABLE_CHECK[_ENFORCED], which is similar. - It conditionally works with the ptep_modify_prot API. It will be bypassed when e.g. XEN PV is enabled, however still work for most of the rest scenarios, which should be the common cases so should be good enough. - Hugetlb check is a bit hairy, as the page table check cannot identify hugetlb pte or normal pte via trapping at set_pte_at(), because of the current design where hugetlb maps every layers to pte_t... For example, the default set_huge_pte_at() can invoke set_pte_at() directly and lose the hugetlb context, treating it the same as a normal pte_t. So far it's fine because we have huge_pte_uffd_wp() always equals to pte_uffd_wp() as long as supported (x86 only). It'll be a bigger problem when we'll define _PAGE_UFFD_WP differently at various pgtable levels, because then one huge_pte_uffd_wp() per-arch will stop making sense first.. as of now we can leave this for later too. This patch also removes commit c2da319c2e altogether, as we have something better now. [1] https://lore.kernel.org/all/000000000000dce0530615c89210@google.com/ Link: https://lkml.kernel.org/r/20240417212549.2766883-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-04-17 21:25:49 +00:00
#include <linux/swap.h>
#include <linux/swapops.h>
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
#undef pr_fmt
#define pr_fmt(fmt) "page_table_check: " fmt
struct page_table_check {
atomic_t anon_map_count;
atomic_t file_map_count;
};
static bool __page_table_check_enabled __initdata =
IS_ENABLED(CONFIG_PAGE_TABLE_CHECK_ENFORCED);
DEFINE_STATIC_KEY_TRUE(page_table_check_disabled);
EXPORT_SYMBOL(page_table_check_disabled);
static int __init early_page_table_check_param(char *buf)
{
return kstrtobool(buf, &__page_table_check_enabled);
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
}
early_param("page_table_check", early_page_table_check_param);
static bool __init need_page_table_check(void)
{
return __page_table_check_enabled;
}
static void __init init_page_table_check(void)
{
if (!__page_table_check_enabled)
return;
static_branch_disable(&page_table_check_disabled);
}
struct page_ext_operations page_table_check_ops = {
.size = sizeof(struct page_table_check),
.need = need_page_table_check,
.init = init_page_table_check,
.need_shared_flags = false,
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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};
static struct page_table_check *get_page_table_check(struct page_ext *page_ext)
{
BUG_ON(!page_ext);
return page_ext_data(page_ext, &page_table_check_ops);
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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}
/*
* An entry is removed from the page table, decrement the counters for that page
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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* verify that it is of correct type and counters do not become negative.
*/
static void page_table_check_clear(unsigned long pfn, unsigned long pgcnt)
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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{
struct page_ext *page_ext;
struct page *page;
unsigned long i;
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bool anon;
if (!pfn_valid(pfn))
return;
page = pfn_to_page(pfn);
mm: fix use-after free of page_ext after race with memory-offline The below is one path where race between page_ext and offline of the respective memory blocks will cause use-after-free on the access of page_ext structure. process1 process2 --------- --------- a)doing /proc/page_owner doing memory offline through offline_pages. b) PageBuddy check is failed thus proceed to get the page_owner information through page_ext access. page_ext = lookup_page_ext(page); migrate_pages(); ................. Since all pages are successfully migrated as part of the offline operation,send MEM_OFFLINE notification where for page_ext it calls: offline_page_ext()--> __free_page_ext()--> free_page_ext()--> vfree(ms->page_ext) mem_section->page_ext = NULL c) Check for the PAGE_EXT flags in the page_ext->flags access results into the use-after-free (leading to the translation faults). As mentioned above, there is really no synchronization between page_ext access and its freeing in the memory_offline. The memory offline steps(roughly) on a memory block is as below: 1) Isolate all the pages 2) while(1) try free the pages to buddy.(->free_list[MIGRATE_ISOLATE]) 3) delete the pages from this buddy list. 4) Then free page_ext.(Note: The struct page is still alive as it is freed only during hot remove of the memory which frees the memmap, which steps the user might not perform). This design leads to the state where struct page is alive but the struct page_ext is freed, where the later is ideally part of the former which just representing the page_flags (check [3] for why this design is chosen). The abovementioned race is just one example __but the problem persists in the other paths too involving page_ext->flags access(eg: page_is_idle())__. Fix all the paths where offline races with page_ext access by maintaining synchronization with rcu lock and is achieved in 3 steps: 1) Invalidate all the page_ext's of the sections of a memory block by storing a flag in the LSB of mem_section->page_ext. 2) Wait until all the existing readers to finish working with the ->page_ext's with synchronize_rcu(). Any parallel process that starts after this call will not get page_ext, through lookup_page_ext(), for the block parallel offline operation is being performed. 3) Now safely free all sections ->page_ext's of the block on which offline operation is being performed. Note: If synchronize_rcu() takes time then optimizations can be done in this path through call_rcu()[2]. Thanks to David Hildenbrand for his views/suggestions on the initial discussion[1] and Pavan kondeti for various inputs on this patch. [1] https://lore.kernel.org/linux-mm/59edde13-4167-8550-86f0-11fc67882107@quicinc.com/ [2] https://lore.kernel.org/all/a26ce299-aed1-b8ad-711e-a49e82bdd180@quicinc.com/T/#u [3] https://lore.kernel.org/all/6fa6b7aa-731e-891c-3efb-a03d6a700efa@redhat.com/ [quic_charante@quicinc.com: rename label `loop' to `ext_put_continue' per David] Link: https://lkml.kernel.org/r/1661496993-11473-1-git-send-email-quic_charante@quicinc.com Link: https://lkml.kernel.org/r/1660830600-9068-1-git-send-email-quic_charante@quicinc.com Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com> Suggested-by: David Hildenbrand <david@redhat.com> Suggested-by: Michal Hocko <mhocko@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Fernand Sieber <sieberf@amazon.com> Cc: Minchan Kim <minchan@google.com> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Pavan Kondeti <quic_pkondeti@quicinc.com> Cc: SeongJae Park <sjpark@amazon.de> Cc: Shakeel Butt <shakeelb@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: William Kucharski <william.kucharski@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-08-18 13:50:00 +00:00
page_ext = page_ext_get(page);
if (!page_ext)
return;
BUG_ON(PageSlab(page));
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
anon = PageAnon(page);
for (i = 0; i < pgcnt; i++) {
struct page_table_check *ptc = get_page_table_check(page_ext);
if (anon) {
BUG_ON(atomic_read(&ptc->file_map_count));
BUG_ON(atomic_dec_return(&ptc->anon_map_count) < 0);
} else {
BUG_ON(atomic_read(&ptc->anon_map_count));
BUG_ON(atomic_dec_return(&ptc->file_map_count) < 0);
}
page_ext = page_ext_next(page_ext);
}
mm: fix use-after free of page_ext after race with memory-offline The below is one path where race between page_ext and offline of the respective memory blocks will cause use-after-free on the access of page_ext structure. process1 process2 --------- --------- a)doing /proc/page_owner doing memory offline through offline_pages. b) PageBuddy check is failed thus proceed to get the page_owner information through page_ext access. page_ext = lookup_page_ext(page); migrate_pages(); ................. Since all pages are successfully migrated as part of the offline operation,send MEM_OFFLINE notification where for page_ext it calls: offline_page_ext()--> __free_page_ext()--> free_page_ext()--> vfree(ms->page_ext) mem_section->page_ext = NULL c) Check for the PAGE_EXT flags in the page_ext->flags access results into the use-after-free (leading to the translation faults). As mentioned above, there is really no synchronization between page_ext access and its freeing in the memory_offline. The memory offline steps(roughly) on a memory block is as below: 1) Isolate all the pages 2) while(1) try free the pages to buddy.(->free_list[MIGRATE_ISOLATE]) 3) delete the pages from this buddy list. 4) Then free page_ext.(Note: The struct page is still alive as it is freed only during hot remove of the memory which frees the memmap, which steps the user might not perform). This design leads to the state where struct page is alive but the struct page_ext is freed, where the later is ideally part of the former which just representing the page_flags (check [3] for why this design is chosen). The abovementioned race is just one example __but the problem persists in the other paths too involving page_ext->flags access(eg: page_is_idle())__. Fix all the paths where offline races with page_ext access by maintaining synchronization with rcu lock and is achieved in 3 steps: 1) Invalidate all the page_ext's of the sections of a memory block by storing a flag in the LSB of mem_section->page_ext. 2) Wait until all the existing readers to finish working with the ->page_ext's with synchronize_rcu(). Any parallel process that starts after this call will not get page_ext, through lookup_page_ext(), for the block parallel offline operation is being performed. 3) Now safely free all sections ->page_ext's of the block on which offline operation is being performed. Note: If synchronize_rcu() takes time then optimizations can be done in this path through call_rcu()[2]. Thanks to David Hildenbrand for his views/suggestions on the initial discussion[1] and Pavan kondeti for various inputs on this patch. [1] https://lore.kernel.org/linux-mm/59edde13-4167-8550-86f0-11fc67882107@quicinc.com/ [2] https://lore.kernel.org/all/a26ce299-aed1-b8ad-711e-a49e82bdd180@quicinc.com/T/#u [3] https://lore.kernel.org/all/6fa6b7aa-731e-891c-3efb-a03d6a700efa@redhat.com/ [quic_charante@quicinc.com: rename label `loop' to `ext_put_continue' per David] Link: https://lkml.kernel.org/r/1661496993-11473-1-git-send-email-quic_charante@quicinc.com Link: https://lkml.kernel.org/r/1660830600-9068-1-git-send-email-quic_charante@quicinc.com Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com> Suggested-by: David Hildenbrand <david@redhat.com> Suggested-by: Michal Hocko <mhocko@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Fernand Sieber <sieberf@amazon.com> Cc: Minchan Kim <minchan@google.com> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Pavan Kondeti <quic_pkondeti@quicinc.com> Cc: SeongJae Park <sjpark@amazon.de> Cc: Shakeel Butt <shakeelb@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: William Kucharski <william.kucharski@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-08-18 13:50:00 +00:00
page_ext_put(page_ext);
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
}
/*
* A new entry is added to the page table, increment the counters for that page
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
* verify that it is of correct type and is not being mapped with a different
* type to a different process.
*/
static void page_table_check_set(unsigned long pfn, unsigned long pgcnt,
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
bool rw)
{
struct page_ext *page_ext;
struct page *page;
unsigned long i;
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
bool anon;
if (!pfn_valid(pfn))
return;
page = pfn_to_page(pfn);
mm: fix use-after free of page_ext after race with memory-offline The below is one path where race between page_ext and offline of the respective memory blocks will cause use-after-free on the access of page_ext structure. process1 process2 --------- --------- a)doing /proc/page_owner doing memory offline through offline_pages. b) PageBuddy check is failed thus proceed to get the page_owner information through page_ext access. page_ext = lookup_page_ext(page); migrate_pages(); ................. Since all pages are successfully migrated as part of the offline operation,send MEM_OFFLINE notification where for page_ext it calls: offline_page_ext()--> __free_page_ext()--> free_page_ext()--> vfree(ms->page_ext) mem_section->page_ext = NULL c) Check for the PAGE_EXT flags in the page_ext->flags access results into the use-after-free (leading to the translation faults). As mentioned above, there is really no synchronization between page_ext access and its freeing in the memory_offline. The memory offline steps(roughly) on a memory block is as below: 1) Isolate all the pages 2) while(1) try free the pages to buddy.(->free_list[MIGRATE_ISOLATE]) 3) delete the pages from this buddy list. 4) Then free page_ext.(Note: The struct page is still alive as it is freed only during hot remove of the memory which frees the memmap, which steps the user might not perform). This design leads to the state where struct page is alive but the struct page_ext is freed, where the later is ideally part of the former which just representing the page_flags (check [3] for why this design is chosen). The abovementioned race is just one example __but the problem persists in the other paths too involving page_ext->flags access(eg: page_is_idle())__. Fix all the paths where offline races with page_ext access by maintaining synchronization with rcu lock and is achieved in 3 steps: 1) Invalidate all the page_ext's of the sections of a memory block by storing a flag in the LSB of mem_section->page_ext. 2) Wait until all the existing readers to finish working with the ->page_ext's with synchronize_rcu(). Any parallel process that starts after this call will not get page_ext, through lookup_page_ext(), for the block parallel offline operation is being performed. 3) Now safely free all sections ->page_ext's of the block on which offline operation is being performed. Note: If synchronize_rcu() takes time then optimizations can be done in this path through call_rcu()[2]. Thanks to David Hildenbrand for his views/suggestions on the initial discussion[1] and Pavan kondeti for various inputs on this patch. [1] https://lore.kernel.org/linux-mm/59edde13-4167-8550-86f0-11fc67882107@quicinc.com/ [2] https://lore.kernel.org/all/a26ce299-aed1-b8ad-711e-a49e82bdd180@quicinc.com/T/#u [3] https://lore.kernel.org/all/6fa6b7aa-731e-891c-3efb-a03d6a700efa@redhat.com/ [quic_charante@quicinc.com: rename label `loop' to `ext_put_continue' per David] Link: https://lkml.kernel.org/r/1661496993-11473-1-git-send-email-quic_charante@quicinc.com Link: https://lkml.kernel.org/r/1660830600-9068-1-git-send-email-quic_charante@quicinc.com Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com> Suggested-by: David Hildenbrand <david@redhat.com> Suggested-by: Michal Hocko <mhocko@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Fernand Sieber <sieberf@amazon.com> Cc: Minchan Kim <minchan@google.com> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Pavan Kondeti <quic_pkondeti@quicinc.com> Cc: SeongJae Park <sjpark@amazon.de> Cc: Shakeel Butt <shakeelb@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: William Kucharski <william.kucharski@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-08-18 13:50:00 +00:00
page_ext = page_ext_get(page);
if (!page_ext)
return;
BUG_ON(PageSlab(page));
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
anon = PageAnon(page);
for (i = 0; i < pgcnt; i++) {
struct page_table_check *ptc = get_page_table_check(page_ext);
if (anon) {
BUG_ON(atomic_read(&ptc->file_map_count));
BUG_ON(atomic_inc_return(&ptc->anon_map_count) > 1 && rw);
} else {
BUG_ON(atomic_read(&ptc->anon_map_count));
BUG_ON(atomic_inc_return(&ptc->file_map_count) < 0);
}
page_ext = page_ext_next(page_ext);
}
mm: fix use-after free of page_ext after race with memory-offline The below is one path where race between page_ext and offline of the respective memory blocks will cause use-after-free on the access of page_ext structure. process1 process2 --------- --------- a)doing /proc/page_owner doing memory offline through offline_pages. b) PageBuddy check is failed thus proceed to get the page_owner information through page_ext access. page_ext = lookup_page_ext(page); migrate_pages(); ................. Since all pages are successfully migrated as part of the offline operation,send MEM_OFFLINE notification where for page_ext it calls: offline_page_ext()--> __free_page_ext()--> free_page_ext()--> vfree(ms->page_ext) mem_section->page_ext = NULL c) Check for the PAGE_EXT flags in the page_ext->flags access results into the use-after-free (leading to the translation faults). As mentioned above, there is really no synchronization between page_ext access and its freeing in the memory_offline. The memory offline steps(roughly) on a memory block is as below: 1) Isolate all the pages 2) while(1) try free the pages to buddy.(->free_list[MIGRATE_ISOLATE]) 3) delete the pages from this buddy list. 4) Then free page_ext.(Note: The struct page is still alive as it is freed only during hot remove of the memory which frees the memmap, which steps the user might not perform). This design leads to the state where struct page is alive but the struct page_ext is freed, where the later is ideally part of the former which just representing the page_flags (check [3] for why this design is chosen). The abovementioned race is just one example __but the problem persists in the other paths too involving page_ext->flags access(eg: page_is_idle())__. Fix all the paths where offline races with page_ext access by maintaining synchronization with rcu lock and is achieved in 3 steps: 1) Invalidate all the page_ext's of the sections of a memory block by storing a flag in the LSB of mem_section->page_ext. 2) Wait until all the existing readers to finish working with the ->page_ext's with synchronize_rcu(). Any parallel process that starts after this call will not get page_ext, through lookup_page_ext(), for the block parallel offline operation is being performed. 3) Now safely free all sections ->page_ext's of the block on which offline operation is being performed. Note: If synchronize_rcu() takes time then optimizations can be done in this path through call_rcu()[2]. Thanks to David Hildenbrand for his views/suggestions on the initial discussion[1] and Pavan kondeti for various inputs on this patch. [1] https://lore.kernel.org/linux-mm/59edde13-4167-8550-86f0-11fc67882107@quicinc.com/ [2] https://lore.kernel.org/all/a26ce299-aed1-b8ad-711e-a49e82bdd180@quicinc.com/T/#u [3] https://lore.kernel.org/all/6fa6b7aa-731e-891c-3efb-a03d6a700efa@redhat.com/ [quic_charante@quicinc.com: rename label `loop' to `ext_put_continue' per David] Link: https://lkml.kernel.org/r/1661496993-11473-1-git-send-email-quic_charante@quicinc.com Link: https://lkml.kernel.org/r/1660830600-9068-1-git-send-email-quic_charante@quicinc.com Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com> Suggested-by: David Hildenbrand <david@redhat.com> Suggested-by: Michal Hocko <mhocko@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Fernand Sieber <sieberf@amazon.com> Cc: Minchan Kim <minchan@google.com> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Pavan Kondeti <quic_pkondeti@quicinc.com> Cc: SeongJae Park <sjpark@amazon.de> Cc: Shakeel Butt <shakeelb@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: William Kucharski <william.kucharski@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-08-18 13:50:00 +00:00
page_ext_put(page_ext);
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
}
/*
* page is on free list, or is being allocated, verify that counters are zeroes
* crash if they are not.
*/
void __page_table_check_zero(struct page *page, unsigned int order)
{
mm: fix use-after free of page_ext after race with memory-offline The below is one path where race between page_ext and offline of the respective memory blocks will cause use-after-free on the access of page_ext structure. process1 process2 --------- --------- a)doing /proc/page_owner doing memory offline through offline_pages. b) PageBuddy check is failed thus proceed to get the page_owner information through page_ext access. page_ext = lookup_page_ext(page); migrate_pages(); ................. Since all pages are successfully migrated as part of the offline operation,send MEM_OFFLINE notification where for page_ext it calls: offline_page_ext()--> __free_page_ext()--> free_page_ext()--> vfree(ms->page_ext) mem_section->page_ext = NULL c) Check for the PAGE_EXT flags in the page_ext->flags access results into the use-after-free (leading to the translation faults). As mentioned above, there is really no synchronization between page_ext access and its freeing in the memory_offline. The memory offline steps(roughly) on a memory block is as below: 1) Isolate all the pages 2) while(1) try free the pages to buddy.(->free_list[MIGRATE_ISOLATE]) 3) delete the pages from this buddy list. 4) Then free page_ext.(Note: The struct page is still alive as it is freed only during hot remove of the memory which frees the memmap, which steps the user might not perform). This design leads to the state where struct page is alive but the struct page_ext is freed, where the later is ideally part of the former which just representing the page_flags (check [3] for why this design is chosen). The abovementioned race is just one example __but the problem persists in the other paths too involving page_ext->flags access(eg: page_is_idle())__. Fix all the paths where offline races with page_ext access by maintaining synchronization with rcu lock and is achieved in 3 steps: 1) Invalidate all the page_ext's of the sections of a memory block by storing a flag in the LSB of mem_section->page_ext. 2) Wait until all the existing readers to finish working with the ->page_ext's with synchronize_rcu(). Any parallel process that starts after this call will not get page_ext, through lookup_page_ext(), for the block parallel offline operation is being performed. 3) Now safely free all sections ->page_ext's of the block on which offline operation is being performed. Note: If synchronize_rcu() takes time then optimizations can be done in this path through call_rcu()[2]. Thanks to David Hildenbrand for his views/suggestions on the initial discussion[1] and Pavan kondeti for various inputs on this patch. [1] https://lore.kernel.org/linux-mm/59edde13-4167-8550-86f0-11fc67882107@quicinc.com/ [2] https://lore.kernel.org/all/a26ce299-aed1-b8ad-711e-a49e82bdd180@quicinc.com/T/#u [3] https://lore.kernel.org/all/6fa6b7aa-731e-891c-3efb-a03d6a700efa@redhat.com/ [quic_charante@quicinc.com: rename label `loop' to `ext_put_continue' per David] Link: https://lkml.kernel.org/r/1661496993-11473-1-git-send-email-quic_charante@quicinc.com Link: https://lkml.kernel.org/r/1660830600-9068-1-git-send-email-quic_charante@quicinc.com Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com> Suggested-by: David Hildenbrand <david@redhat.com> Suggested-by: Michal Hocko <mhocko@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Fernand Sieber <sieberf@amazon.com> Cc: Minchan Kim <minchan@google.com> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Pavan Kondeti <quic_pkondeti@quicinc.com> Cc: SeongJae Park <sjpark@amazon.de> Cc: Shakeel Butt <shakeelb@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: William Kucharski <william.kucharski@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-08-18 13:50:00 +00:00
struct page_ext *page_ext;
unsigned long i;
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
BUG_ON(PageSlab(page));
mm: fix use-after free of page_ext after race with memory-offline The below is one path where race between page_ext and offline of the respective memory blocks will cause use-after-free on the access of page_ext structure. process1 process2 --------- --------- a)doing /proc/page_owner doing memory offline through offline_pages. b) PageBuddy check is failed thus proceed to get the page_owner information through page_ext access. page_ext = lookup_page_ext(page); migrate_pages(); ................. Since all pages are successfully migrated as part of the offline operation,send MEM_OFFLINE notification where for page_ext it calls: offline_page_ext()--> __free_page_ext()--> free_page_ext()--> vfree(ms->page_ext) mem_section->page_ext = NULL c) Check for the PAGE_EXT flags in the page_ext->flags access results into the use-after-free (leading to the translation faults). As mentioned above, there is really no synchronization between page_ext access and its freeing in the memory_offline. The memory offline steps(roughly) on a memory block is as below: 1) Isolate all the pages 2) while(1) try free the pages to buddy.(->free_list[MIGRATE_ISOLATE]) 3) delete the pages from this buddy list. 4) Then free page_ext.(Note: The struct page is still alive as it is freed only during hot remove of the memory which frees the memmap, which steps the user might not perform). This design leads to the state where struct page is alive but the struct page_ext is freed, where the later is ideally part of the former which just representing the page_flags (check [3] for why this design is chosen). The abovementioned race is just one example __but the problem persists in the other paths too involving page_ext->flags access(eg: page_is_idle())__. Fix all the paths where offline races with page_ext access by maintaining synchronization with rcu lock and is achieved in 3 steps: 1) Invalidate all the page_ext's of the sections of a memory block by storing a flag in the LSB of mem_section->page_ext. 2) Wait until all the existing readers to finish working with the ->page_ext's with synchronize_rcu(). Any parallel process that starts after this call will not get page_ext, through lookup_page_ext(), for the block parallel offline operation is being performed. 3) Now safely free all sections ->page_ext's of the block on which offline operation is being performed. Note: If synchronize_rcu() takes time then optimizations can be done in this path through call_rcu()[2]. Thanks to David Hildenbrand for his views/suggestions on the initial discussion[1] and Pavan kondeti for various inputs on this patch. [1] https://lore.kernel.org/linux-mm/59edde13-4167-8550-86f0-11fc67882107@quicinc.com/ [2] https://lore.kernel.org/all/a26ce299-aed1-b8ad-711e-a49e82bdd180@quicinc.com/T/#u [3] https://lore.kernel.org/all/6fa6b7aa-731e-891c-3efb-a03d6a700efa@redhat.com/ [quic_charante@quicinc.com: rename label `loop' to `ext_put_continue' per David] Link: https://lkml.kernel.org/r/1661496993-11473-1-git-send-email-quic_charante@quicinc.com Link: https://lkml.kernel.org/r/1660830600-9068-1-git-send-email-quic_charante@quicinc.com Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com> Suggested-by: David Hildenbrand <david@redhat.com> Suggested-by: Michal Hocko <mhocko@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Fernand Sieber <sieberf@amazon.com> Cc: Minchan Kim <minchan@google.com> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Pavan Kondeti <quic_pkondeti@quicinc.com> Cc: SeongJae Park <sjpark@amazon.de> Cc: Shakeel Butt <shakeelb@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: William Kucharski <william.kucharski@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-08-18 13:50:00 +00:00
page_ext = page_ext_get(page);
if (!page_ext)
return;
for (i = 0; i < (1ul << order); i++) {
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
struct page_table_check *ptc = get_page_table_check(page_ext);
BUG_ON(atomic_read(&ptc->anon_map_count));
BUG_ON(atomic_read(&ptc->file_map_count));
page_ext = page_ext_next(page_ext);
}
mm: fix use-after free of page_ext after race with memory-offline The below is one path where race between page_ext and offline of the respective memory blocks will cause use-after-free on the access of page_ext structure. process1 process2 --------- --------- a)doing /proc/page_owner doing memory offline through offline_pages. b) PageBuddy check is failed thus proceed to get the page_owner information through page_ext access. page_ext = lookup_page_ext(page); migrate_pages(); ................. Since all pages are successfully migrated as part of the offline operation,send MEM_OFFLINE notification where for page_ext it calls: offline_page_ext()--> __free_page_ext()--> free_page_ext()--> vfree(ms->page_ext) mem_section->page_ext = NULL c) Check for the PAGE_EXT flags in the page_ext->flags access results into the use-after-free (leading to the translation faults). As mentioned above, there is really no synchronization between page_ext access and its freeing in the memory_offline. The memory offline steps(roughly) on a memory block is as below: 1) Isolate all the pages 2) while(1) try free the pages to buddy.(->free_list[MIGRATE_ISOLATE]) 3) delete the pages from this buddy list. 4) Then free page_ext.(Note: The struct page is still alive as it is freed only during hot remove of the memory which frees the memmap, which steps the user might not perform). This design leads to the state where struct page is alive but the struct page_ext is freed, where the later is ideally part of the former which just representing the page_flags (check [3] for why this design is chosen). The abovementioned race is just one example __but the problem persists in the other paths too involving page_ext->flags access(eg: page_is_idle())__. Fix all the paths where offline races with page_ext access by maintaining synchronization with rcu lock and is achieved in 3 steps: 1) Invalidate all the page_ext's of the sections of a memory block by storing a flag in the LSB of mem_section->page_ext. 2) Wait until all the existing readers to finish working with the ->page_ext's with synchronize_rcu(). Any parallel process that starts after this call will not get page_ext, through lookup_page_ext(), for the block parallel offline operation is being performed. 3) Now safely free all sections ->page_ext's of the block on which offline operation is being performed. Note: If synchronize_rcu() takes time then optimizations can be done in this path through call_rcu()[2]. Thanks to David Hildenbrand for his views/suggestions on the initial discussion[1] and Pavan kondeti for various inputs on this patch. [1] https://lore.kernel.org/linux-mm/59edde13-4167-8550-86f0-11fc67882107@quicinc.com/ [2] https://lore.kernel.org/all/a26ce299-aed1-b8ad-711e-a49e82bdd180@quicinc.com/T/#u [3] https://lore.kernel.org/all/6fa6b7aa-731e-891c-3efb-a03d6a700efa@redhat.com/ [quic_charante@quicinc.com: rename label `loop' to `ext_put_continue' per David] Link: https://lkml.kernel.org/r/1661496993-11473-1-git-send-email-quic_charante@quicinc.com Link: https://lkml.kernel.org/r/1660830600-9068-1-git-send-email-quic_charante@quicinc.com Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com> Suggested-by: David Hildenbrand <david@redhat.com> Suggested-by: Michal Hocko <mhocko@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Fernand Sieber <sieberf@amazon.com> Cc: Minchan Kim <minchan@google.com> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Pavan Kondeti <quic_pkondeti@quicinc.com> Cc: SeongJae Park <sjpark@amazon.de> Cc: Shakeel Butt <shakeelb@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: William Kucharski <william.kucharski@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-08-18 13:50:00 +00:00
page_ext_put(page_ext);
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
}
void __page_table_check_pte_clear(struct mm_struct *mm, pte_t pte)
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
{
if (&init_mm == mm)
return;
if (pte_user_accessible_page(pte)) {
page_table_check_clear(pte_pfn(pte), PAGE_SIZE >> PAGE_SHIFT);
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
}
}
EXPORT_SYMBOL(__page_table_check_pte_clear);
void __page_table_check_pmd_clear(struct mm_struct *mm, pmd_t pmd)
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
{
if (&init_mm == mm)
return;
if (pmd_user_accessible_page(pmd)) {
page_table_check_clear(pmd_pfn(pmd), PMD_SIZE >> PAGE_SHIFT);
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
}
}
EXPORT_SYMBOL(__page_table_check_pmd_clear);
void __page_table_check_pud_clear(struct mm_struct *mm, pud_t pud)
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
{
if (&init_mm == mm)
return;
if (pud_user_accessible_page(pud)) {
page_table_check_clear(pud_pfn(pud), PUD_SIZE >> PAGE_SHIFT);
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
}
}
EXPORT_SYMBOL(__page_table_check_pud_clear);
mm/page_table_check: support userfault wr-protect entries Allow page_table_check hooks to check over userfaultfd wr-protect criteria upon pgtable updates. The rule is no co-existance allowed for any writable flag against userfault wr-protect flag. This should be better than c2da319c2e, where we used to only sanitize such issues during a pgtable walk, but when hitting such issue we don't have a good chance to know where does that writable bit came from [1], so that even the pgtable walk exposes a kernel bug (which is still helpful on triaging) but not easy to track and debug. Now we switch to track the source. It's much easier too with the recent introduction of page table check. There are some limitations with using the page table check here for userfaultfd wr-protect purpose: - It is only enabled with explicit enablement of page table check configs and/or boot parameters, but should be good enough to track at least syzbot issues, as syzbot should enable PAGE_TABLE_CHECK[_ENFORCED] for x86 [1]. We used to have DEBUG_VM but it's now off for most distros, while distros also normally not enable PAGE_TABLE_CHECK[_ENFORCED], which is similar. - It conditionally works with the ptep_modify_prot API. It will be bypassed when e.g. XEN PV is enabled, however still work for most of the rest scenarios, which should be the common cases so should be good enough. - Hugetlb check is a bit hairy, as the page table check cannot identify hugetlb pte or normal pte via trapping at set_pte_at(), because of the current design where hugetlb maps every layers to pte_t... For example, the default set_huge_pte_at() can invoke set_pte_at() directly and lose the hugetlb context, treating it the same as a normal pte_t. So far it's fine because we have huge_pte_uffd_wp() always equals to pte_uffd_wp() as long as supported (x86 only). It'll be a bigger problem when we'll define _PAGE_UFFD_WP differently at various pgtable levels, because then one huge_pte_uffd_wp() per-arch will stop making sense first.. as of now we can leave this for later too. This patch also removes commit c2da319c2e altogether, as we have something better now. [1] https://lore.kernel.org/all/000000000000dce0530615c89210@google.com/ Link: https://lkml.kernel.org/r/20240417212549.2766883-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-04-17 21:25:49 +00:00
/* Whether the swap entry cached writable information */
static inline bool swap_cached_writable(swp_entry_t entry)
{
return is_writable_device_exclusive_entry(entry) ||
is_writable_device_private_entry(entry) ||
is_writable_migration_entry(entry);
}
static inline void page_table_check_pte_flags(pte_t pte)
{
if (pte_present(pte) && pte_uffd_wp(pte))
WARN_ON_ONCE(pte_write(pte));
else if (is_swap_pte(pte) && pte_swp_uffd_wp(pte))
WARN_ON_ONCE(swap_cached_writable(pte_to_swp_entry(pte)));
}
void __page_table_check_ptes_set(struct mm_struct *mm, pte_t *ptep, pte_t pte,
unsigned int nr)
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
{
unsigned int i;
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
if (&init_mm == mm)
return;
mm/page_table_check: support userfault wr-protect entries Allow page_table_check hooks to check over userfaultfd wr-protect criteria upon pgtable updates. The rule is no co-existance allowed for any writable flag against userfault wr-protect flag. This should be better than c2da319c2e, where we used to only sanitize such issues during a pgtable walk, but when hitting such issue we don't have a good chance to know where does that writable bit came from [1], so that even the pgtable walk exposes a kernel bug (which is still helpful on triaging) but not easy to track and debug. Now we switch to track the source. It's much easier too with the recent introduction of page table check. There are some limitations with using the page table check here for userfaultfd wr-protect purpose: - It is only enabled with explicit enablement of page table check configs and/or boot parameters, but should be good enough to track at least syzbot issues, as syzbot should enable PAGE_TABLE_CHECK[_ENFORCED] for x86 [1]. We used to have DEBUG_VM but it's now off for most distros, while distros also normally not enable PAGE_TABLE_CHECK[_ENFORCED], which is similar. - It conditionally works with the ptep_modify_prot API. It will be bypassed when e.g. XEN PV is enabled, however still work for most of the rest scenarios, which should be the common cases so should be good enough. - Hugetlb check is a bit hairy, as the page table check cannot identify hugetlb pte or normal pte via trapping at set_pte_at(), because of the current design where hugetlb maps every layers to pte_t... For example, the default set_huge_pte_at() can invoke set_pte_at() directly and lose the hugetlb context, treating it the same as a normal pte_t. So far it's fine because we have huge_pte_uffd_wp() always equals to pte_uffd_wp() as long as supported (x86 only). It'll be a bigger problem when we'll define _PAGE_UFFD_WP differently at various pgtable levels, because then one huge_pte_uffd_wp() per-arch will stop making sense first.. as of now we can leave this for later too. This patch also removes commit c2da319c2e altogether, as we have something better now. [1] https://lore.kernel.org/all/000000000000dce0530615c89210@google.com/ Link: https://lkml.kernel.org/r/20240417212549.2766883-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-04-17 21:25:49 +00:00
page_table_check_pte_flags(pte);
for (i = 0; i < nr; i++)
__page_table_check_pte_clear(mm, ptep_get(ptep + i));
if (pte_user_accessible_page(pte))
page_table_check_set(pte_pfn(pte), nr, pte_write(pte));
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
}
EXPORT_SYMBOL(__page_table_check_ptes_set);
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
mm/page_table_check: support userfault wr-protect entries Allow page_table_check hooks to check over userfaultfd wr-protect criteria upon pgtable updates. The rule is no co-existance allowed for any writable flag against userfault wr-protect flag. This should be better than c2da319c2e, where we used to only sanitize such issues during a pgtable walk, but when hitting such issue we don't have a good chance to know where does that writable bit came from [1], so that even the pgtable walk exposes a kernel bug (which is still helpful on triaging) but not easy to track and debug. Now we switch to track the source. It's much easier too with the recent introduction of page table check. There are some limitations with using the page table check here for userfaultfd wr-protect purpose: - It is only enabled with explicit enablement of page table check configs and/or boot parameters, but should be good enough to track at least syzbot issues, as syzbot should enable PAGE_TABLE_CHECK[_ENFORCED] for x86 [1]. We used to have DEBUG_VM but it's now off for most distros, while distros also normally not enable PAGE_TABLE_CHECK[_ENFORCED], which is similar. - It conditionally works with the ptep_modify_prot API. It will be bypassed when e.g. XEN PV is enabled, however still work for most of the rest scenarios, which should be the common cases so should be good enough. - Hugetlb check is a bit hairy, as the page table check cannot identify hugetlb pte or normal pte via trapping at set_pte_at(), because of the current design where hugetlb maps every layers to pte_t... For example, the default set_huge_pte_at() can invoke set_pte_at() directly and lose the hugetlb context, treating it the same as a normal pte_t. So far it's fine because we have huge_pte_uffd_wp() always equals to pte_uffd_wp() as long as supported (x86 only). It'll be a bigger problem when we'll define _PAGE_UFFD_WP differently at various pgtable levels, because then one huge_pte_uffd_wp() per-arch will stop making sense first.. as of now we can leave this for later too. This patch also removes commit c2da319c2e altogether, as we have something better now. [1] https://lore.kernel.org/all/000000000000dce0530615c89210@google.com/ Link: https://lkml.kernel.org/r/20240417212549.2766883-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-04-17 21:25:49 +00:00
static inline void page_table_check_pmd_flags(pmd_t pmd)
{
if (pmd_present(pmd) && pmd_uffd_wp(pmd))
WARN_ON_ONCE(pmd_write(pmd));
else if (is_swap_pmd(pmd) && pmd_swp_uffd_wp(pmd))
WARN_ON_ONCE(swap_cached_writable(pmd_to_swp_entry(pmd)));
}
void __page_table_check_pmd_set(struct mm_struct *mm, pmd_t *pmdp, pmd_t pmd)
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
{
if (&init_mm == mm)
return;
mm/page_table_check: support userfault wr-protect entries Allow page_table_check hooks to check over userfaultfd wr-protect criteria upon pgtable updates. The rule is no co-existance allowed for any writable flag against userfault wr-protect flag. This should be better than c2da319c2e, where we used to only sanitize such issues during a pgtable walk, but when hitting such issue we don't have a good chance to know where does that writable bit came from [1], so that even the pgtable walk exposes a kernel bug (which is still helpful on triaging) but not easy to track and debug. Now we switch to track the source. It's much easier too with the recent introduction of page table check. There are some limitations with using the page table check here for userfaultfd wr-protect purpose: - It is only enabled with explicit enablement of page table check configs and/or boot parameters, but should be good enough to track at least syzbot issues, as syzbot should enable PAGE_TABLE_CHECK[_ENFORCED] for x86 [1]. We used to have DEBUG_VM but it's now off for most distros, while distros also normally not enable PAGE_TABLE_CHECK[_ENFORCED], which is similar. - It conditionally works with the ptep_modify_prot API. It will be bypassed when e.g. XEN PV is enabled, however still work for most of the rest scenarios, which should be the common cases so should be good enough. - Hugetlb check is a bit hairy, as the page table check cannot identify hugetlb pte or normal pte via trapping at set_pte_at(), because of the current design where hugetlb maps every layers to pte_t... For example, the default set_huge_pte_at() can invoke set_pte_at() directly and lose the hugetlb context, treating it the same as a normal pte_t. So far it's fine because we have huge_pte_uffd_wp() always equals to pte_uffd_wp() as long as supported (x86 only). It'll be a bigger problem when we'll define _PAGE_UFFD_WP differently at various pgtable levels, because then one huge_pte_uffd_wp() per-arch will stop making sense first.. as of now we can leave this for later too. This patch also removes commit c2da319c2e altogether, as we have something better now. [1] https://lore.kernel.org/all/000000000000dce0530615c89210@google.com/ Link: https://lkml.kernel.org/r/20240417212549.2766883-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-04-17 21:25:49 +00:00
page_table_check_pmd_flags(pmd);
__page_table_check_pmd_clear(mm, *pmdp);
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
if (pmd_user_accessible_page(pmd)) {
page_table_check_set(pmd_pfn(pmd), PMD_SIZE >> PAGE_SHIFT,
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
pmd_write(pmd));
}
}
EXPORT_SYMBOL(__page_table_check_pmd_set);
void __page_table_check_pud_set(struct mm_struct *mm, pud_t *pudp, pud_t pud)
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
{
if (&init_mm == mm)
return;
__page_table_check_pud_clear(mm, *pudp);
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
if (pud_user_accessible_page(pud)) {
page_table_check_set(pud_pfn(pud), PUD_SIZE >> PAGE_SHIFT,
mm: page table check Check user page table entries at the time they are added and removed. Allows to synchronously catch memory corruption issues related to double mapping. When a pte for an anonymous page is added into page table, we verify that this pte does not already point to a file backed page, and vice versa if this is a file backed page that is being added we verify that this page does not have an anonymous mapping We also enforce that read-only sharing for anonymous pages is allowed (i.e. cow after fork). All other sharing must be for file pages. Page table check allows to protect and debug cases where "struct page" metadata became corrupted for some reason. For example, when refcnt or mapcount become invalid. Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-14 22:06:37 +00:00
pud_write(pud));
}
}
EXPORT_SYMBOL(__page_table_check_pud_set);
mm/page_table_check: check entries at pmd levels syzbot detected a case where the page table counters were not properly updated. syzkaller login: ------------[ cut here ]------------ kernel BUG at mm/page_table_check.c:162! invalid opcode: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 3099 Comm: pasha Not tainted 5.16.0+ #48 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIO4 RIP: 0010:__page_table_check_zero+0x159/0x1a0 Call Trace: free_pcp_prepare+0x3be/0xaa0 free_unref_page+0x1c/0x650 free_compound_page+0xec/0x130 free_transhuge_page+0x1be/0x260 __put_compound_page+0x90/0xd0 release_pages+0x54c/0x1060 __pagevec_release+0x7c/0x110 shmem_undo_range+0x85e/0x1250 ... The repro involved having a huge page that is split due to uprobe event temporarily replacing one of the pages in the huge page. Later the huge page was combined again, but the counters were off, as the PTE level was not properly updated. Make sure that when PMD is cleared and prior to freeing the level the PTEs are updated. Link: https://lkml.kernel.org/r/20220131203249.2832273-5-pasha.tatashin@soleen.com Fixes: df4e817b7108 ("mm: page table check") Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Greg Thelen <gthelen@google.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-02-04 04:49:24 +00:00
void __page_table_check_pte_clear_range(struct mm_struct *mm,
unsigned long addr,
pmd_t pmd)
{
if (&init_mm == mm)
return;
if (!pmd_bad(pmd) && !pmd_leaf(pmd)) {
pte_t *ptep = pte_offset_map(&pmd, addr);
unsigned long i;
mm/debug_vm_pgtable,page_table_check: warn pte map fails Failures here would be surprising: pte_advanced_tests() and pte_clear_tests() and __page_table_check_pte_clear_range() each issue a warning if pte_offset_map() or pte_offset_map_lock() fails. Link: https://lkml.kernel.org/r/3ea9e4f-e5cf-d7d9-4c2-291b3c5a3636@google.com Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Christoph Hellwig <hch@infradead.org> Cc: David Hildenbrand <david@redhat.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: SeongJae Park <sj@kernel.org> Cc: Song Liu <song@kernel.org> Cc: Steven Price <steven.price@arm.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com> Cc: Will Deacon <will@kernel.org> Cc: Yang Shi <shy828301@gmail.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Zack Rusin <zackr@vmware.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-09 01:27:52 +00:00
if (WARN_ON(!ptep))
return;
mm/page_table_check: check entries at pmd levels syzbot detected a case where the page table counters were not properly updated. syzkaller login: ------------[ cut here ]------------ kernel BUG at mm/page_table_check.c:162! invalid opcode: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 3099 Comm: pasha Not tainted 5.16.0+ #48 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIO4 RIP: 0010:__page_table_check_zero+0x159/0x1a0 Call Trace: free_pcp_prepare+0x3be/0xaa0 free_unref_page+0x1c/0x650 free_compound_page+0xec/0x130 free_transhuge_page+0x1be/0x260 __put_compound_page+0x90/0xd0 release_pages+0x54c/0x1060 __pagevec_release+0x7c/0x110 shmem_undo_range+0x85e/0x1250 ... The repro involved having a huge page that is split due to uprobe event temporarily replacing one of the pages in the huge page. Later the huge page was combined again, but the counters were off, as the PTE level was not properly updated. Make sure that when PMD is cleared and prior to freeing the level the PTEs are updated. Link: https://lkml.kernel.org/r/20220131203249.2832273-5-pasha.tatashin@soleen.com Fixes: df4e817b7108 ("mm: page table check") Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Greg Thelen <gthelen@google.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-02-04 04:49:24 +00:00
for (i = 0; i < PTRS_PER_PTE; i++) {
__page_table_check_pte_clear(mm, ptep_get(ptep));
mm/page_table_check: check entries at pmd levels syzbot detected a case where the page table counters were not properly updated. syzkaller login: ------------[ cut here ]------------ kernel BUG at mm/page_table_check.c:162! invalid opcode: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 3099 Comm: pasha Not tainted 5.16.0+ #48 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIO4 RIP: 0010:__page_table_check_zero+0x159/0x1a0 Call Trace: free_pcp_prepare+0x3be/0xaa0 free_unref_page+0x1c/0x650 free_compound_page+0xec/0x130 free_transhuge_page+0x1be/0x260 __put_compound_page+0x90/0xd0 release_pages+0x54c/0x1060 __pagevec_release+0x7c/0x110 shmem_undo_range+0x85e/0x1250 ... The repro involved having a huge page that is split due to uprobe event temporarily replacing one of the pages in the huge page. Later the huge page was combined again, but the counters were off, as the PTE level was not properly updated. Make sure that when PMD is cleared and prior to freeing the level the PTEs are updated. Link: https://lkml.kernel.org/r/20220131203249.2832273-5-pasha.tatashin@soleen.com Fixes: df4e817b7108 ("mm: page table check") Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Greg Thelen <gthelen@google.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-02-04 04:49:24 +00:00
addr += PAGE_SIZE;
ptep++;
}
pte_unmap(ptep - PTRS_PER_PTE);
mm/page_table_check: check entries at pmd levels syzbot detected a case where the page table counters were not properly updated. syzkaller login: ------------[ cut here ]------------ kernel BUG at mm/page_table_check.c:162! invalid opcode: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 3099 Comm: pasha Not tainted 5.16.0+ #48 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIO4 RIP: 0010:__page_table_check_zero+0x159/0x1a0 Call Trace: free_pcp_prepare+0x3be/0xaa0 free_unref_page+0x1c/0x650 free_compound_page+0xec/0x130 free_transhuge_page+0x1be/0x260 __put_compound_page+0x90/0xd0 release_pages+0x54c/0x1060 __pagevec_release+0x7c/0x110 shmem_undo_range+0x85e/0x1250 ... The repro involved having a huge page that is split due to uprobe event temporarily replacing one of the pages in the huge page. Later the huge page was combined again, but the counters were off, as the PTE level was not properly updated. Make sure that when PMD is cleared and prior to freeing the level the PTEs are updated. Link: https://lkml.kernel.org/r/20220131203249.2832273-5-pasha.tatashin@soleen.com Fixes: df4e817b7108 ("mm: page table check") Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Greg Thelen <gthelen@google.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Paul Turner <pjt@google.com> Cc: Wei Xu <weixugc@google.com> Cc: Will Deacon <will@kernel.org> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-02-04 04:49:24 +00:00
}
}