mm/mempool.c: kasan: poison mempool elements

Mempools keep allocated objects in reserved for situations when ordinary allocation may not be possible to satisfy. These objects shouldn't be accessed before they leave the pool. This patch poison elements when get into the pool and unpoison when they leave it. This will let KASan to detect use-after-free of mempool's elements. Signed-off-by: Andrey Ryabinin <[email protected]> Tested-by: David Rientjes <[email protected]> Cc: Catalin Marinas <[email protected]> Cc: Dmitry Chernenkov <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: Alexander Potapenko <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
ambv · Apr 15, 2015 · 9239361 · 9239361
1 parent bda6d33
commit 9239361
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diff --git a/include/linux/kasan.h b/include/linux/kasan.h
@@ -44,6 +44,7 @@ void kasan_poison_object_data(struct kmem_cache *cache, void *object);
 
 void kasan_kmalloc_large(const void *ptr, size_t size);
 void kasan_kfree_large(const void *ptr);
+void kasan_kfree(void *ptr);
 void kasan_kmalloc(struct kmem_cache *s, const void *object, size_t size);
 void kasan_krealloc(const void *object, size_t new_size);
 
@@ -71,6 +72,7 @@ static inline void kasan_poison_object_data(struct kmem_cache *cache,
 
 static inline void kasan_kmalloc_large(void *ptr, size_t size) {}
 static inline void kasan_kfree_large(const void *ptr) {}
+static inline void kasan_kfree(void *ptr) {}
 static inline void kasan_kmalloc(struct kmem_cache *s, const void *object,
 				size_t size) {}
 static inline void kasan_krealloc(const void *object, size_t new_size) {}

diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
@@ -389,6 +389,19 @@ void kasan_krealloc(const void *object, size_t size)
 		kasan_kmalloc(page->slab_cache, object, size);
 }
 
+void kasan_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_slab_free(page->slab_cache, ptr);
+}
+
 void kasan_kfree_large(const void *ptr)
 {
 	struct page *page = virt_to_page(ptr);

diff --git a/mm/mempool.c b/mm/mempool.c
@@ -12,6 +12,7 @@
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/highmem.h>
+#include <linux/kasan.h>
 #include <linux/kmemleak.h>
 #include <linux/export.h>
 #include <linux/mempool.h>
@@ -101,10 +102,31 @@ static inline void poison_element(mempool_t *pool, void *element)
 }
 #endif /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
 
+static void kasan_poison_element(mempool_t *pool, void *element)
+{
+	if (pool->alloc == mempool_alloc_slab)
+		kasan_slab_free(pool->pool_data, element);
+	if (pool->alloc == mempool_kmalloc)
+		kasan_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)
+{
+	if (pool->alloc == mempool_alloc_slab)
+		kasan_slab_alloc(pool->pool_data, element);
+	if (pool->alloc == mempool_kmalloc)
+		kasan_krealloc(element, (size_t)pool->pool_data);
+	if (pool->alloc == mempool_alloc_pages)
+		kasan_alloc_pages(element, (unsigned long)pool->pool_data);
+}
+
 static void add_element(mempool_t *pool, void *element)
 {
 	BUG_ON(pool->curr_nr >= pool->min_nr);
 	poison_element(pool, element);
+	kasan_poison_element(pool, element);
 	pool->elements[pool->curr_nr++] = element;
 }
 
@@ -114,6 +136,7 @@ static void *remove_element(mempool_t *pool)
 
 	BUG_ON(pool->curr_nr < 0);
 	check_element(pool, element);
+	kasan_unpoison_element(pool, element);
 	return element;
 }