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authorDmitry Vyukov <dvyukov@google.com>2018-02-07 02:36:34 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2018-02-07 05:32:43 +0300
commit1db0e0f9dd9816e5d018518f933066d7b9bc0e33 (patch)
treeff58cbb66f85207a812ad0e60c9eb66f5cef9620 /mm
parent6860f6340c0918cddcd3c9fcf8c36401c8184268 (diff)
downloadlinux-1db0e0f9dd9816e5d018518f933066d7b9bc0e33.tar.xz
kasan: unify code between kasan_slab_free() and kasan_poison_kfree()
Both of these functions deal with freeing of slab objects. However, kasan_poison_kfree() mishandles SLAB_TYPESAFE_BY_RCU (must also not poison such objects) and does not detect double-frees. Unify code between these functions. This solves both of the problems and allows to add more common code (e.g. detection of invalid frees). Link: http://lkml.kernel.org/r/385493d863acf60408be219a021c3c8e27daa96f.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>
Diffstat (limited to 'mm')
-rw-r--r--mm/kasan/kasan.c28
1 files changed, 12 insertions, 16 deletions
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 77c103748728..578843fab5dc 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -489,21 +489,11 @@ void kasan_slab_alloc(struct kmem_cache *cache, void *object, gfp_t flags)
kasan_kmalloc(cache, object, cache->object_size, flags);
}
-static void kasan_poison_slab_free(struct kmem_cache *cache, void *object)
-{
- unsigned long size = cache->object_size;
- unsigned long rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
-
- /* RCU slabs could be legally used after free within the RCU period */
- if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
- return;
-
- kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
-}
-
-bool kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
+static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
+ unsigned long ip, bool quarantine)
{
s8 shadow_byte;
+ unsigned long rounded_up_size;
/* RCU slabs could be legally used after free within the RCU period */
if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
@@ -515,9 +505,10 @@ bool kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
return true;
}
- kasan_poison_slab_free(cache, object);
+ rounded_up_size = round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE);
+ kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
- if (unlikely(!(cache->flags & SLAB_KASAN)))
+ if (!quarantine || unlikely(!(cache->flags & SLAB_KASAN)))
return false;
set_track(&get_alloc_info(cache, object)->free_track, GFP_NOWAIT);
@@ -525,6 +516,11 @@ bool kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
return true;
}
+bool kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
+{
+ return __kasan_slab_free(cache, object, ip, true);
+}
+
void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size,
gfp_t flags)
{
@@ -602,7 +598,7 @@ void kasan_poison_kfree(void *ptr, unsigned long ip)
kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
KASAN_FREE_PAGE);
} else {
- kasan_poison_slab_free(page->slab_cache, ptr);
+ __kasan_slab_free(page->slab_cache, ptr, ip, false);
}
}