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mm: mempool: kasan: don't poot mempool objects in quarantine

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Currently we may put reserved by mempool elements into quarantine via
kasan_kfree().  This is totally wrong since quarantine may really free
these objects.  So when mempool will try to use such element,
use-after-free will happen.  Or mempool may decide that it no longer
need that element and double-free it.

So don't put object into quarantine in kasan_kfree(), just poison it.
Rename kasan_kfree() to kasan_poison_kfree() to respect that.

Also, we shouldn't use kasan_slab_alloc()/kasan_krealloc() in
kasan_unpoison_element() because those functions may update allocation
stacktrace.  This would be wrong for the most of the remove_element call
sites.

(The only call site where we may want to update alloc stacktrace is
 in mempool_alloc(). Kmemleak solves this by calling
 kmemleak_update_trace(), so we could make something like that too.
 But this is out of scope of this patch).

Fixes: 55834c5909 ("mm: kasan: initial memory quarantine implementation")
Link: http://lkml.kernel.org/r/575977C3.1010905@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reported-by: Kuthonuzo Luruo <kuthonuzo.luruo@hpe.com>
Acked-by: Alexander Potapenko <glider@google.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrey Ryabinin 2016-06-24 14:49:34 -07:00 committed by Linus Torvalds
parent a6921c2974
commit 9b75a867cc
3 changed files with 14 additions and 15 deletions
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11
include/linux/kasan.h
View file

@ -59,14 +59,13 @@ void kasan_poison_object_data(struct kmem_cache *cache, void *object);
void kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags);
void kasan_kfree_large(const void *ptr);
void kasan_kfree(void *ptr);
void kasan_poison_kfree(void *ptr);
void kasan_kmalloc(struct kmem_cache *s, const void *object, size_t size,
gfp_t flags);
void kasan_krealloc(const void *object, size_t new_size, gfp_t flags);
void kasan_slab_alloc(struct kmem_cache *s, void *object, gfp_t flags);
bool kasan_slab_free(struct kmem_cache *s, void *object);
void kasan_poison_slab_free(struct kmem_cache *s, void *object);
struct kasan_cache {
int alloc_meta_offset;
@ -76,6 +75,9 @@ struct kasan_cache {
int kasan_module_alloc(void *addr, size_t size);
void kasan_free_shadow(const struct vm_struct *vm);
size_t ksize(const void *);
static inline void kasan_unpoison_slab(const void *ptr) { ksize(ptr); }
#else /* CONFIG_KASAN */
static inline void kasan_unpoison_shadow(const void *address, size_t size) {}
@ -102,7 +104,7 @@ static inline void kasan_poison_object_data(struct kmem_cache *cache,
static inline void kasan_kmalloc_large(void *ptr, size_t size, gfp_t flags) {}
static inline void kasan_kfree_large(const void *ptr) {}
static inline void kasan_kfree(void *ptr) {}
static inline void kasan_poison_kfree(void *ptr) {}
static inline void kasan_kmalloc(struct kmem_cache *s, const void *object,
size_t size, gfp_t flags) {}
static inline void kasan_krealloc(const void *object, size_t new_size,
@ -114,11 +116,12 @@ static inline bool kasan_slab_free(struct kmem_cache *s, void *object)
{
return false;
}
static inline void kasan_poison_slab_free(struct kmem_cache *s, void *object) {}
static inline int kasan_module_alloc(void *addr, size_t size) { return 0; }
static inline void kasan_free_shadow(const struct vm_struct *vm) {}
static inline void kasan_unpoison_slab(const void *ptr) { }
#endif /* CONFIG_KASAN */
#endif /* LINUX_KASAN_H */

6
mm/kasan/kasan.c
View file

@ -508,7 +508,7 @@ void kasan_slab_alloc(struct kmem_cache *cache, void *object, gfp_t flags)
kasan_kmalloc(cache, object, cache->object_size, flags);
}
void kasan_poison_slab_free(struct kmem_cache *cache, void *object)
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);
@ -626,7 +626,7 @@ void kasan_krealloc(const void *object, size_t size, gfp_t flags)
kasan_kmalloc(page->slab_cache, object, size, flags);
}
void kasan_kfree(void *ptr)
void kasan_poison_kfree(void *ptr)
{
struct page *page;
@ -636,7 +636,7 @@ void kasan_kfree(void *ptr)
kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
KASAN_FREE_PAGE);
else
kasan_slab_free(page->slab_cache, ptr);
kasan_poison_slab_free(page->slab_cache, ptr);
}
void kasan_kfree_large(const void *ptr)

12
mm/mempool.c
View file

@ -104,20 +104,16 @@ static inline void poison_element(mempool_t *pool, void *element)
static void kasan_poison_element(mempool_t *pool, void *element)
{
if (pool->alloc == mempool_alloc_slab)
kasan_poison_slab_free(pool->pool_data, element);
if (pool->alloc == mempool_kmalloc)
kasan_kfree(element);
if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
kasan_poison_kfree(element);
if (pool->alloc == mempool_alloc_pages)
kasan_free_pages(element, (unsigned long)pool->pool_data);
}
static void kasan_unpoison_element(mempool_t *pool, void *element, gfp_t flags)
{
if (pool->alloc == mempool_alloc_slab)
kasan_slab_alloc(pool->pool_data, element, flags);
if (pool->alloc == mempool_kmalloc)
kasan_krealloc(element, (size_t)pool->pool_data, flags);
if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
kasan_unpoison_slab(element);
if (pool->alloc == mempool_alloc_pages)
kasan_alloc_pages(element, (unsigned long)pool->pool_data);
}