From 9b75a867cc9ddbafcaf35029358ac500f2635ff3 Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Fri, 24 Jun 2016 14:49:34 -0700 Subject: 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 --- mm/kasan/kasan.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'mm/kasan') 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) -- cgit v1.2.3