From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f69.google.com (mail-wm0-f69.google.com [74.125.82.69]) by kanga.kvack.org (Postfix) with ESMTP id 8DD716B025E for ; Wed, 27 Dec 2017 07:44:46 -0500 (EST) Received: by mail-wm0-f69.google.com with SMTP id w141so9828387wme.1 for ; Wed, 27 Dec 2017 04:44:46 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id v72sor9017703wrb.36.2017.12.27.04.44.45 for (Google Transport Security); Wed, 27 Dec 2017 04:44:45 -0800 (PST) From: Dmitry Vyukov Subject: [PATCH 3/5] kasan: detect invalid frees for large mempool objects Date: Wed, 27 Dec 2017 13:44:34 +0100 Message-Id: In-Reply-To: References: In-Reply-To: References: Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org, aryabinin@virtuozzo.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, Dmitry Vyukov Detect frees of pointers into middle of mempool objects. I did a one-off test, but it turned out to be very tricky, so I reverted it. First, mempool does not call kasan_poison_kfree() unless allocation function fails. I stubbed an allocation function to fail on second and subsequent allocations. But then mempool stopped to call kasan_poison_kfree() at all, because it does it only when allocation function is mempool_kmalloc(). We could support this special failing test allocation function in mempool, but it also can't live with kasan tests, because these are in a module. Signed-off-by: Dmitry Vyukov Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Cc: kasan-dev@googlegroups.com --- include/linux/kasan.h | 4 ++-- mm/kasan/kasan.c | 11 ++++++++--- mm/mempool.c | 6 +++--- 3 files changed, 13 insertions(+), 8 deletions(-) diff --git a/include/linux/kasan.h b/include/linux/kasan.h index f0d13c30acc6..fc45f8952d1e 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -57,7 +57,7 @@ void kasan_init_slab_obj(struct kmem_cache *cache, const void *object); void kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags); void kasan_kfree_large(void *ptr, unsigned long ip); -void kasan_poison_kfree(void *ptr); +void kasan_poison_kfree(void *ptr, unsigned long ip); 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); @@ -109,7 +109,7 @@ static inline void kasan_init_slab_obj(struct kmem_cache *cache, static inline void kasan_kmalloc_large(void *ptr, size_t size, gfp_t flags) {} static inline void kasan_kfree_large(void *ptr, unsigned long ip) {} -static inline void kasan_poison_kfree(void *ptr) {} +static inline void kasan_poison_kfree(void *ptr, unsigned long ip) {} 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, diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c index 32f555ded938..77c103748728 100644 --- a/mm/kasan/kasan.c +++ b/mm/kasan/kasan.c @@ -588,17 +588,22 @@ void kasan_krealloc(const void *object, size_t size, gfp_t flags) kasan_kmalloc(page->slab_cache, object, size, flags); } -void kasan_poison_kfree(void *ptr) +void kasan_poison_kfree(void *ptr, unsigned long ip) { struct page *page; page = virt_to_head_page(ptr); - if (unlikely(!PageSlab(page))) + if (unlikely(!PageSlab(page))) { + if (ptr != page_address(page)) { + kasan_report_invalid_free(ptr, ip); + return; + } kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page), KASAN_FREE_PAGE); - else + } else { kasan_poison_slab_free(page->slab_cache, ptr); + } } void kasan_kfree_large(void *ptr, unsigned long ip) diff --git a/mm/mempool.c b/mm/mempool.c index 7d8c5a0010a2..5c9dce34719b 100644 --- a/mm/mempool.c +++ b/mm/mempool.c @@ -103,10 +103,10 @@ 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) +static __always_inline void kasan_poison_element(mempool_t *pool, void *element) { if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc) - kasan_poison_kfree(element); + kasan_poison_kfree(element, _RET_IP_); if (pool->alloc == mempool_alloc_pages) kasan_free_pages(element, (unsigned long)pool->pool_data); } @@ -119,7 +119,7 @@ static void kasan_unpoison_element(mempool_t *pool, void *element, gfp_t flags) kasan_alloc_pages(element, (unsigned long)pool->pool_data); } -static void add_element(mempool_t *pool, void *element) +static __always_inline void add_element(mempool_t *pool, void *element) { BUG_ON(pool->curr_nr >= pool->min_nr); poison_element(pool, element); -- 2.15.1.620.gb9897f4670-goog -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org