From 9b75a867cc9ddbafcaf35029358ac500f2635ff3 Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Fri, 24 Jun 2016 14:49:34 -0700 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") Link: http://lkml.kernel.org/r/575977C3.1010905@virtuozzo.com Signed-off-by: Andrey Ryabinin Reported-by: Kuthonuzo Luruo Acked-by: Alexander Potapenko Cc: Dmitriy Vyukov Cc: Kostya Serebryany Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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 611927f5870d..ac4b3c46a84d 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 28439acda6ec..6845f9294696 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 9e075f829d0d..8f65464da5de 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); } -- 2.20.1