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kasan: detect invalid frees

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Detect frees of pointers into middle of heap objects.

Link: http://lkml.kernel.org/r/cb569193190356beb018a03bb8d6fbae67e7adbc.1514378558.git.dvyukov@google.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>a
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dmitry Vyukov 2018-02-06 15:36:37 -08:00 committed by Linus Torvalds
parent 1db0e0f9dd
commit b1d5728939
2 changed files with 56 additions and 0 deletions
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50
lib/test_kasan.c
View File

@ -523,6 +523,54 @@ static noinline void __init kasan_alloca_oob_right(void)
*(volatile char *)p;
}
static noinline void __init kmem_cache_double_free(void)
{
char *p;
size_t size = 200;
struct kmem_cache *cache;
cache = kmem_cache_create("test_cache", size, 0, 0, NULL);
if (!cache) {
pr_err("Cache allocation failed\n");
return;
}
pr_info("double-free on heap object\n");
p = kmem_cache_alloc(cache, GFP_KERNEL);
if (!p) {
pr_err("Allocation failed\n");
kmem_cache_destroy(cache);
return;
}
kmem_cache_free(cache, p);
kmem_cache_free(cache, p);
kmem_cache_destroy(cache);
}
static noinline void __init kmem_cache_invalid_free(void)
{
char *p;
size_t size = 200;
struct kmem_cache *cache;
cache = kmem_cache_create("test_cache", size, 0, SLAB_TYPESAFE_BY_RCU,
NULL);
if (!cache) {
pr_err("Cache allocation failed\n");
return;
}
pr_info("invalid-free of heap object\n");
p = kmem_cache_alloc(cache, GFP_KERNEL);
if (!p) {
pr_err("Allocation failed\n");
kmem_cache_destroy(cache);
return;
}
kmem_cache_free(cache, p + 1);
kmem_cache_destroy(cache);
}
static int __init kmalloc_tests_init(void)
{
/*
@ -560,6 +608,8 @@ static int __init kmalloc_tests_init(void)
ksize_unpoisons_memory();
copy_user_test();
use_after_scope_test();
kmem_cache_double_free();
kmem_cache_invalid_free();
kasan_restore_multi_shot(multishot);

6
mm/kasan/kasan.c
View File

@ -495,6 +495,12 @@ static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
s8 shadow_byte;
unsigned long rounded_up_size;
if (unlikely(nearest_obj(cache, virt_to_head_page(object), object) !=
object)) {
kasan_report_invalid_free(object, ip);
return true;
}
/* RCU slabs could be legally used after free within the RCU period */
if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
return false;