From: Andrey Ryabinin a.ryabinin@samsung.com
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 a.ryabinin@samsung.com Tested-by: David Rientjes rientjes@google.com Cc: Catalin Marinas catalin.marinas@arm.com Cc: Dmitry Chernenkov drcheren@gmail.com Cc: Dmitry Vyukov dvyukov@google.com Cc: Alexander Potapenko glider@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org (cherry picked from commit 923936157b158f36bd6a3d86496dce82b1a957de) Signed-off-by: Alex Shi alex.shi@linaro.org --- include/linux/kasan.h | 2 ++ mm/kasan/kasan.c | 13 +++++++++++++ mm/mempool.c | 23 +++++++++++++++++++++++ 3 files changed, 38 insertions(+)
diff --git a/include/linux/kasan.h b/include/linux/kasan.h index f4ffd04..4b9f85c 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -52,6 +52,7 @@ 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);
@@ -79,6 +80,7 @@ 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 index 936d816..6c513a6 100644 --- 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 index 2884d5b..2cc08de 100644 --- 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; }