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lkdtm/heap: add tests for freelist hardening

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This adds tests for double free and cross-cache freeing, which should both
be caught by CONFIG_SLAB_FREELIST_HARDENED.

Link: http://lkml.kernel.org/r/20190530045017.15252-4-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Alexander Popov <alex.popov@linux.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kees Cook 2019-07-11 20:53:29 -07:00 committed by Linus Torvalds
parent a64b53780e
commit 966fede8e4
3 changed files with 82 additions and 0 deletions
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5
drivers/misc/lkdtm/core.c
View File

@ -120,6 +120,9 @@ static const struct crashtype crashtypes[] = {
CRASHTYPE(READ_AFTER_FREE),
CRASHTYPE(WRITE_BUDDY_AFTER_FREE),
CRASHTYPE(READ_BUDDY_AFTER_FREE),
CRASHTYPE(SLAB_FREE_DOUBLE),
CRASHTYPE(SLAB_FREE_CROSS),
CRASHTYPE(SLAB_FREE_PAGE),
CRASHTYPE(SOFTLOCKUP),
CRASHTYPE(HARDLOCKUP),
CRASHTYPE(SPINLOCKUP),
@ -426,6 +429,7 @@ static int __init lkdtm_module_init(void)
lkdtm_bugs_init(&recur_count);
lkdtm_perms_init();
lkdtm_usercopy_init();
lkdtm_heap_init();
/* Register debugfs interface */
lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
@ -472,6 +476,7 @@ static void __exit lkdtm_module_exit(void)
debugfs_remove_recursive(lkdtm_debugfs_root);
/* Handle test-specific clean-up. */
lkdtm_heap_exit();
lkdtm_usercopy_exit();
if (lkdtm_kprobe != NULL)

72
drivers/misc/lkdtm/heap.c
View File

@ -7,6 +7,10 @@
#include <linux/slab.h>
#include <linux/sched.h>
static struct kmem_cache *double_free_cache;
static struct kmem_cache *a_cache;
static struct kmem_cache *b_cache;
/*
* This tries to stay within the next largest power-of-2 kmalloc cache
* to avoid actually overwriting anything important if it's not detected
@ -146,3 +150,71 @@ void lkdtm_READ_BUDDY_AFTER_FREE(void)
kfree(val);
}
void lkdtm_SLAB_FREE_DOUBLE(void)
{
int *val;
val = kmem_cache_alloc(double_free_cache, GFP_KERNEL);
if (!val) {
pr_info("Unable to allocate double_free_cache memory.\n");
return;
}
/* Just make sure we got real memory. */
*val = 0x12345678;
pr_info("Attempting double slab free ...\n");
kmem_cache_free(double_free_cache, val);
kmem_cache_free(double_free_cache, val);
}
void lkdtm_SLAB_FREE_CROSS(void)
{
int *val;
val = kmem_cache_alloc(a_cache, GFP_KERNEL);
if (!val) {
pr_info("Unable to allocate a_cache memory.\n");
return;
}
/* Just make sure we got real memory. */
*val = 0x12345679;
pr_info("Attempting cross-cache slab free ...\n");
kmem_cache_free(b_cache, val);
}
void lkdtm_SLAB_FREE_PAGE(void)
{
unsigned long p = __get_free_page(GFP_KERNEL);
pr_info("Attempting non-Slab slab free ...\n");
kmem_cache_free(NULL, (void *)p);
free_page(p);
}
/*
* We have constructors to keep the caches distinctly separated without
* needing to boot with "slab_nomerge".
*/
static void ctor_double_free(void *region)
{ }
static void ctor_a(void *region)
{ }
static void ctor_b(void *region)
{ }
void __init lkdtm_heap_init(void)
{
double_free_cache = kmem_cache_create("lkdtm-heap-double_free",
64, 0, 0, ctor_double_free);
a_cache = kmem_cache_create("lkdtm-heap-a", 64, 0, 0, ctor_a);
b_cache = kmem_cache_create("lkdtm-heap-b", 64, 0, 0, ctor_b);
}
void __exit lkdtm_heap_exit(void)
{
kmem_cache_destroy(double_free_cache);
kmem_cache_destroy(a_cache);
kmem_cache_destroy(b_cache);
}

5
drivers/misc/lkdtm/lkdtm.h
View File

@ -28,11 +28,16 @@ void lkdtm_STACK_GUARD_PAGE_LEADING(void);
void lkdtm_STACK_GUARD_PAGE_TRAILING(void);
/* lkdtm_heap.c */
void __init lkdtm_heap_init(void);
void __exit lkdtm_heap_exit(void);
void lkdtm_OVERWRITE_ALLOCATION(void);
void lkdtm_WRITE_AFTER_FREE(void);
void lkdtm_READ_AFTER_FREE(void);
void lkdtm_WRITE_BUDDY_AFTER_FREE(void);
void lkdtm_READ_BUDDY_AFTER_FREE(void);
void lkdtm_SLAB_FREE_DOUBLE(void);
void lkdtm_SLAB_FREE_CROSS(void);
void lkdtm_SLAB_FREE_PAGE(void);
/* lkdtm_perms.c */
void __init lkdtm_perms_init(void);