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uprobes: use vm_special_mapping close() functionality
The following KASAN splat was shown:
[ 44.505448] ================================================================== 20:37:27 [3421/145075]
[ 44.505455] BUG: KASAN: slab-use-after-free in special_mapping_close+0x9c/0xc8
[ 44.505471] Read of size 8 at addr 00000000868dac48 by task sh/1384
[ 44.505479]
[ 44.505486] CPU: 51 UID: 0 PID: 1384 Comm: sh Not tainted 6.11.0-rc6-next-20240902-dirty #1496
[ 44.505503] Hardware name: IBM 3931 A01 704 (z/VM 7.3.0)
[ 44.505508] Call Trace:
[ 44.505511] [<000b0324d2f78080>] dump_stack_lvl+0xd0/0x108
[ 44.505521] [<000b0324d2f5435c>] print_address_description.constprop.0+0x34/0x2e0
[ 44.505529] [<000b0324d2f5464c>] print_report+0x44/0x138
[ 44.505536] [<000b0324d1383192>] kasan_report+0xc2/0x140
[ 44.505543] [<000b0324d2f52904>] special_mapping_close+0x9c/0xc8
[ 44.505550] [<000b0324d12c7978>] remove_vma+0x78/0x120
[ 44.505557] [<000b0324d128a2c6>] exit_mmap+0x326/0x750
[ 44.505563] [<000b0324d0ba655a>] __mmput+0x9a/0x370
[ 44.505570] [<000b0324d0bbfbe0>] exit_mm+0x240/0x340
[ 44.505575] [<000b0324d0bc0228>] do_exit+0x548/0xd70
[ 44.505580] [<000b0324d0bc1102>] do_group_exit+0x132/0x390
[ 44.505586] [<000b0324d0bc13b6>] __s390x_sys_exit_group+0x56/0x60
[ 44.505592] [<000b0324d0adcbd6>] do_syscall+0x2f6/0x430
[ 44.505599] [<000b0324d2f78434>] __do_syscall+0xa4/0x170
[ 44.505606] [<000b0324d2f9454c>] system_call+0x74/0x98
[ 44.505614]
[ 44.505616] Allocated by task 1384:
[ 44.505621] kasan_save_stack+0x40/0x70
[ 44.505630] kasan_save_track+0x28/0x40
[ 44.505636] __kasan_kmalloc+0xa0/0xc0
[ 44.505642] __create_xol_area+0xfa/0x410
[ 44.505648] get_xol_area+0xb0/0xf0
[ 44.505652] uprobe_notify_resume+0x27a/0x470
[ 44.505657] irqentry_exit_to_user_mode+0x15e/0x1d0
[ 44.505664] pgm_check_handler+0x122/0x170
[ 44.505670]
[ 44.505672] Freed by task 1384:
[ 44.505676] kasan_save_stack+0x40/0x70
[ 44.505682] kasan_save_track+0x28/0x40
[ 44.505687] kasan_save_free_info+0x4a/0x70
[ 44.505693] __kasan_slab_free+0x5a/0x70
[ 44.505698] kfree+0xe8/0x3f0
[ 44.505704] __mmput+0x20/0x370
[ 44.505709] exit_mm+0x240/0x340
[ 44.505713] do_exit+0x548/0xd70
[ 44.505718] do_group_exit+0x132/0x390
[ 44.505722] __s390x_sys_exit_group+0x56/0x60
[ 44.505727] do_syscall+0x2f6/0x430
[ 44.505732] __do_syscall+0xa4/0x170
[ 44.505738] system_call+0x74/0x98
The problem is that uprobe_clear_state() kfree's struct xol_area, which
contains struct vm_special_mapping *xol_mapping. This one is passed to
_install_special_mapping() in xol_add_vma().
__mput reads:
static inline void __mmput(struct mm_struct *mm)
{
VM_BUG_ON(atomic_read(&mm->mm_users));
uprobe_clear_state(mm);
exit_aio(mm);
ksm_exit(mm);
khugepaged_exit(mm); /* must run before exit_mmap */
exit_mmap(mm);
...
}
So uprobe_clear_state() in the beginning free's the memory area
containing the vm_special_mapping data, but exit_mmap() uses this
address later via vma->vm_private_data (which was set in
_install_special_mapping().
Fix this by moving uprobe_clear_state() to uprobes.c and use it as
close() callback.
[usama.anjum@collabora.com: remove unneeded condition]
Link: https://lkml.kernel.org/r/20240906101825.177490-1-usama.anjum@collabora.com
Link: https://lkml.kernel.org/r/20240903073629.2442754-1-svens@linux.ibm.com
Fixes: 223febc6e5 ("mm: add optional close() to struct vm_special_mapping")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Sven Schnelle
Andrew Morton
parent
ec867977fe
commit
08e28de116
@ -126,7 +126,6 @@ extern int uprobe_pre_sstep_notifier(struct pt_regs *regs);
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extern void uprobe_notify_resume(struct pt_regs *regs);
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extern bool uprobe_deny_signal(void);
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extern bool arch_uprobe_skip_sstep(struct arch_uprobe *aup, struct pt_regs *regs);
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extern void uprobe_clear_state(struct mm_struct *mm);
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extern int arch_uprobe_analyze_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long addr);
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extern int arch_uprobe_pre_xol(struct arch_uprobe *aup, struct pt_regs *regs);
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extern int arch_uprobe_post_xol(struct arch_uprobe *aup, struct pt_regs *regs);
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@ -1482,6 +1482,22 @@ void * __weak arch_uprobe_trampoline(unsigned long *psize)
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return &insn;
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}
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/*
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* uprobe_clear_state - Free the area allocated for slots.
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*/
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static void uprobe_clear_state(const struct vm_special_mapping *sm, struct vm_area_struct *vma)
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{
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struct xol_area *area = container_of(vma->vm_private_data, struct xol_area, xol_mapping);
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mutex_lock(&delayed_uprobe_lock);
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delayed_uprobe_remove(NULL, vma->vm_mm);
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mutex_unlock(&delayed_uprobe_lock);
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put_page(area->pages[0]);
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kfree(area->bitmap);
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kfree(area);
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}
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static struct xol_area *__create_xol_area(unsigned long vaddr)
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{
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struct mm_struct *mm = current->mm;
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@ -1500,6 +1516,7 @@ static struct xol_area *__create_xol_area(unsigned long vaddr)
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area->xol_mapping.name = "[uprobes]";
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area->xol_mapping.fault = NULL;
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area->xol_mapping.close = uprobe_clear_state;
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area->xol_mapping.pages = area->pages;
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area->pages[0] = alloc_page(GFP_HIGHUSER);
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if (!area->pages[0])
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@ -1545,25 +1562,6 @@ static struct xol_area *get_xol_area(void)
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return area;
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}
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/*
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* uprobe_clear_state - Free the area allocated for slots.
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*/
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void uprobe_clear_state(struct mm_struct *mm)
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{
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struct xol_area *area = mm->uprobes_state.xol_area;
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mutex_lock(&delayed_uprobe_lock);
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delayed_uprobe_remove(NULL, mm);
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mutex_unlock(&delayed_uprobe_lock);
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if (!area)
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return;
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put_page(area->pages[0]);
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kfree(area->bitmap);
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kfree(area);
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}
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void uprobe_start_dup_mmap(void)
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{
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percpu_down_read(&dup_mmap_sem);
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@ -1338,7 +1338,6 @@ static inline void __mmput(struct mm_struct *mm)
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{
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VM_BUG_ON(atomic_read(&mm->mm_users));
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uprobe_clear_state(mm);
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exit_aio(mm);
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ksm_exit(mm);
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khugepaged_exit(mm); /* must run before exit_mmap */
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