[PATCH] mm: kasan: don't touch metadata in kasan_[un]poison_element()

[PATCH] mm: kasan: don't touch metadata in kasan_[un]poison_element()

[Alexander Potapenko]

To avoid draining the mempools, KASAN shouldn't put the mempool elements
into the quarantine upon mempool_free(). It shouldn't store
allocation/deallocation stacks upon mempool_alloc()/mempool_free() either.
Therefore make kasan_[un]poison_element() just change the shadow memory,
not the metadata.

Signed-off-by: Alexander Potapenko <glider@google.com>
Reported-by: Kuthonuzo Luruo <kuthonuzo.luruo@hpe.com>
---
 include/linux/kasan.h |  8 ++++++--
 mm/kasan/kasan.c      | 48 +++++++++++++++++++++++++++++++++++++++++++++---
 mm/mempool.c          |  5 +++--
 mm/slab.c             |  4 ++--
 mm/slab.h             |  2 +-
 5 files changed, 57 insertions(+), 10 deletions(-)

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 611927f..bafc13a 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -63,8 +63,10 @@ void kasan_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_unpoison_kmalloc(const void *object, size_t size, gfp_t flags);
 
-void kasan_slab_alloc(struct kmem_cache *s, void *object, gfp_t flags);
+void kasan_slab_alloc(struct kmem_cache *s, void *object, bool just_unpoison,
+			gfp_t flags);
 bool kasan_slab_free(struct kmem_cache *s, void *object);
 void kasan_poison_slab_free(struct kmem_cache *s, void *object);
 
@@ -107,9 +109,11 @@ 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,
 				 gfp_t flags) {}
+static inline void kasan_unpoison_kmalloc(const void *object, size_t size,
+					gfp_t flags) {}
 
 static inline void kasan_slab_alloc(struct kmem_cache *s, void *object,
-				   gfp_t flags) {}
+				   bool just_unpoison, gfp_t flags) {}
 static inline bool kasan_slab_free(struct kmem_cache *s, void *object)
 {
 	return false;
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 18b6a2b..8820f22 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -503,9 +503,13 @@ struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
 }
 #endif
 
-void kasan_slab_alloc(struct kmem_cache *cache, void *object, gfp_t flags)
+void kasan_slab_alloc(struct kmem_cache *cache, void *object,
+			bool just_unpoison, gfp_t flags)
 {
-	kasan_kmalloc(cache, object, cache->object_size, flags);
+	if (just_unpoison)
+		kasan_unpoison_shadow(object, cache->object_size);
+	else
+		kasan_kmalloc(cache, object, cache->object_size, flags);
 }
 
 void kasan_poison_slab_free(struct kmem_cache *cache, void *object)
@@ -611,6 +615,31 @@ void kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
 		KASAN_PAGE_REDZONE);
 }
 
+void kasan_unpoison_kmalloc(const void *object, size_t size, gfp_t flags)
+{
+	struct page *page;
+	unsigned long redzone_start;
+	unsigned long redzone_end;
+
+	if (unlikely(object == ZERO_SIZE_PTR) || (object == NULL))
+		return;
+
+	page = virt_to_head_page(object);
+	redzone_start = round_up((unsigned long)(object + size),
+				KASAN_SHADOW_SCALE_SIZE);
+
+	if (unlikely(!PageSlab(page)))
+		redzone_end = (unsigned long)object +
+			(PAGE_SIZE << compound_order(page));
+	else
+		redzone_end = round_up(
+			(unsigned long)object + page->slab_cache->object_size,
+			KASAN_SHADOW_SCALE_SIZE);
+	kasan_unpoison_shadow(object, size);
+	kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
+		KASAN_KMALLOC_REDZONE);
+}
+
 void kasan_krealloc(const void *object, size_t size, gfp_t flags)
 {
 	struct page *page;
@@ -636,7 +665,20 @@ 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_poison_kfree(void *ptr)
+{
+	struct page *page;
+
+	page = virt_to_head_page(ptr);
+
+	if (unlikely(!PageSlab(page)))
+		kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
+				KASAN_FREE_PAGE);
+	else
+		kasan_poison_slab_free(page->slab_cache, ptr);
 }
 
 void kasan_kfree_large(const void *ptr)
diff --git a/mm/mempool.c b/mm/mempool.c
index 9e075f8..bcd48c6 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c
@@ -115,9 +115,10 @@ static void kasan_poison_element(mempool_t *pool, void *element)
 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);
+		kasan_slab_alloc(pool->pool_data, element,
+				/*just_unpoison*/ false, flags);
 	if (pool->alloc == mempool_kmalloc)
-		kasan_krealloc(element, (size_t)pool->pool_data, flags);
+		kasan_unpoison_kmalloc(element, (size_t)pool->pool_data, flags);
 	if (pool->alloc == mempool_alloc_pages)
 		kasan_alloc_pages(element, (unsigned long)pool->pool_data);
 }
diff --git a/mm/slab.c b/mm/slab.c
index cc8bbc1..b42ae23 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3606,7 +3606,7 @@ void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
 {
 	void *ret = slab_alloc(cachep, flags, _RET_IP_);
 
-	kasan_slab_alloc(cachep, ret, flags);
+	kasan_slab_alloc(cachep, ret, /*just_unpoison*/ false, flags);
 	trace_kmem_cache_alloc(_RET_IP_, ret,
 			       cachep->object_size, cachep->size, flags);
 
@@ -3696,7 +3696,7 @@ void *kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid)
 {
 	void *ret = slab_alloc_node(cachep, flags, nodeid, _RET_IP_);
 
-	kasan_slab_alloc(cachep, ret, flags);
+	kasan_slab_alloc(cachep, ret, /*just_unpoison*/ false, flags);
 	trace_kmem_cache_alloc_node(_RET_IP_, ret,
 				    cachep->object_size, cachep->size,
 				    flags, nodeid);
diff --git a/mm/slab.h b/mm/slab.h
index dedb1a9..d56c042 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -405,7 +405,7 @@ static inline void slab_post_alloc_hook(struct kmem_cache *s, gfp_t flags,
 		kmemcheck_slab_alloc(s, flags, object, slab_ksize(s));
 		kmemleak_alloc_recursive(object, s->object_size, 1,
 					 s->flags, flags);
-		kasan_slab_alloc(s, object, flags);
+		kasan_slab_alloc(s, object, /*just_unpoison*/false, flags);
 	}
 	memcg_kmem_put_cache(s);
 }
-- 
2.8.0.rc3.226.g39d4020

Re: [PATCH] mm: kasan: don't touch metadata in kasan_[un]poison_element()

[Andrey Ryabinin]

On 06/01/2016 03:53 PM, Alexander Potapenko wrote:
> To avoid draining the mempools, KASAN shouldn't put the mempool elements
> into the quarantine upon mempool_free().

Correct, but unfortunately this patch doesn't fix that.

> It shouldn't store
> allocation/deallocation stacks upon mempool_alloc()/mempool_free() either.

Why not?

> Therefore make kasan_[un]poison_element() just change the shadow memory,
> not the metadata.
> 
> Signed-off-by: Alexander Potapenko <glider@google.com>
> Reported-by: Kuthonuzo Luruo <kuthonuzo.luruo@hpe.com>
> ---

[...]

> +void kasan_slab_alloc(struct kmem_cache *cache, void *object,
> +			bool just_unpoison, gfp_t flags)
>  {
> -	kasan_kmalloc(cache, object, cache->object_size, flags);
> +	if (just_unpoison)

This set to 'false' in all call sites.

> +		kasan_unpoison_shadow(object, cache->object_size);
> +	else
> +		kasan_kmalloc(cache, object, cache->object_size, flags);
>  }
>  
>  void kasan_poison_slab_free(struct kmem_cache *cache, void *object)
> @@ -611,6 +615,31 @@ void kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
>  		KASAN_PAGE_REDZONE);
>  }
>  
> +void kasan_unpoison_kmalloc(const void *object, size_t size, gfp_t flags)
> +{
> +	struct page *page;
> +	unsigned long redzone_start;
> +	unsigned long redzone_end;
> +
> +	if (unlikely(object == ZERO_SIZE_PTR) || (object == NULL))
> +		return;
> +
> +	page = virt_to_head_page(object);
> +	redzone_start = round_up((unsigned long)(object + size),
> +				KASAN_SHADOW_SCALE_SIZE);
> +
> +	if (unlikely(!PageSlab(page)))
> +		redzone_end = (unsigned long)object +
> +			(PAGE_SIZE << compound_order(page));
> +	else
> +		redzone_end = round_up(
> +			(unsigned long)object + page->slab_cache->object_size,
> +			KASAN_SHADOW_SCALE_SIZE);
> +	kasan_unpoison_shadow(object, size);
> +	kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
> +		KASAN_KMALLOC_REDZONE);
> +}
> +
>  void kasan_krealloc(const void *object, size_t size, gfp_t flags)
>  {
>  	struct page *page;
> @@ -636,7 +665,20 @@ 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_poison_kfree(void *ptr)

Unused

> +{
> +	struct page *page;
> +
> +	page = virt_to_head_page(ptr);
> +
> +	if (unlikely(!PageSlab(page)))
> +		kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
> +				KASAN_FREE_PAGE);
> +	else
> +		kasan_poison_slab_free(page->slab_cache, ptr);
>  }
>  
>  void kasan_kfree_large(const void *ptr)
> diff --git a/mm/mempool.c b/mm/mempool.c
> index 9e075f8..bcd48c6 100644
> --- a/mm/mempool.c
> +++ b/mm/mempool.c
> @@ -115,9 +115,10 @@ static void kasan_poison_element(mempool_t *pool, void *element)
>  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);
> +		kasan_slab_alloc(pool->pool_data, element,
> +				/*just_unpoison*/ false, flags);
>  	if (pool->alloc == mempool_kmalloc)
> -		kasan_krealloc(element, (size_t)pool->pool_data, flags);
> +		kasan_unpoison_kmalloc(element, (size_t)pool->pool_data, flags);

I think, that the current code here is fine.
We only need to fix kasan_poison_element() which calls kasan_kfree() that puts objects into quarantine.

[PATCH] mm: mempool: kasan: don't poot mempool objects in quarantine

[Andrey Ryabinin]

On 06/01/2016 07:22 PM, Andrey Ryabinin wrote:
> 
> 
> On 06/01/2016 03:53 PM, Alexander Potapenko wrote:
>> To avoid draining the mempools, KASAN shouldn't put the mempool elements
>> into the quarantine upon mempool_free().
> 
> Correct, but unfortunately this patch doesn't fix that.
> 

So, I made this:


From: Andrey Ryabinin <aryabinin@virtuozzo.com>
Subject: [PATCH] mm: mempool: kasan: don't poot mempool objects in quarantine

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: 55834c59098d ("mm: kasan: initial memory quarantine implementation")
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reported-by: Kuthonuzo Luruo <kuthonuzo.luruo@hpe.com>
---
 include/linux/kasan.h | 11 +++++++----
 mm/kasan/kasan.c      |  6 +++---
 mm/mempool.c          | 12 ++++--------
 3 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 611927f..ac4b3c4 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -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 */
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 28439ac..6845f92 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -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)
diff --git a/mm/mempool.c b/mm/mempool.c
index 9e075f8..8f65464 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c
@@ -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);
 }
-- 
2.7.3

Re: [PATCH] mm: mempool: kasan: don't poot mempool objects in quarantine

[Alexander Potapenko]

On Thu, Jun 9, 2016 at 4:05 PM, Andrey Ryabinin <aryabinin@virtuozzo.com> wrote:
> On 06/01/2016 07:22 PM, Andrey Ryabinin wrote:
>>
>>
>> On 06/01/2016 03:53 PM, Alexander Potapenko wrote:
>>> To avoid draining the mempools, KASAN shouldn't put the mempool elements
>>> into the quarantine upon mempool_free().
>>
>> Correct, but unfortunately this patch doesn't fix that.
>>
>
> So, I made this:
You beat me to it :)
Thanks!
>
>
> From: Andrey Ryabinin <aryabinin@virtuozzo.com>
> Subject: [PATCH] mm: mempool: kasan: don't poot mempool objects in quarantine
>
> 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: 55834c59098d ("mm: kasan: initial memory quarantine implementation")
> Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
> Reported-by: Kuthonuzo Luruo <kuthonuzo.luruo@hpe.com>
Acked-by: Alexander Potapenko <glider@google.com>
> ---
>  include/linux/kasan.h | 11 +++++++----
>  mm/kasan/kasan.c      |  6 +++---
>  mm/mempool.c          | 12 ++++--------
>  3 files changed, 14 insertions(+), 15 deletions(-)
>
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index 611927f..ac4b3c4 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -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 */
> diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
> index 28439ac..6845f92 100644
> --- a/mm/kasan/kasan.c
> +++ b/mm/kasan/kasan.c
> @@ -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)
> diff --git a/mm/mempool.c b/mm/mempool.c
> index 9e075f8..8f65464 100644
> --- a/mm/mempool.c
> +++ b/mm/mempool.c
> @@ -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);
>  }
> --
> 2.7.3
>
>



-- 
Alexander Potapenko
Software Engineer

Google Germany GmbH
Erika-Mann-Straße, 33
80636 München

Geschäftsführer: Matthew Scott Sucherman, Paul Terence Manicle
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg