From b3cbd9bf77cd1888114dbee1653e79aa23fd4068 Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Tue, 2 Aug 2016 14:02:52 -0700 Subject: mm/kasan: get rid of ->state in struct kasan_alloc_meta The state of object currently tracked in two places - shadow memory, and the ->state field in struct kasan_alloc_meta. We can get rid of the latter. The will save us a little bit of memory. Also, this allow us to move free stack into struct kasan_alloc_meta, without increasing memory consumption. So now we should always know when the last time the object was freed. This may be useful for long delayed use-after-free bugs. As a side effect this fixes following UBSAN warning: UBSAN: Undefined behaviour in mm/kasan/quarantine.c:102:13 member access within misaligned address ffff88000d1efebc for type 'struct qlist_node' which requires 8 byte alignment Link: http://lkml.kernel.org/r/1470062715-14077-5-git-send-email-aryabinin@virtuozzo.com Reported-by: kernel test robot Signed-off-by: Andrey Ryabinin Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/kasan/quarantine.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'mm/kasan/quarantine.c') diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c index 4852625ff851..7fd121d13b88 100644 --- a/mm/kasan/quarantine.c +++ b/mm/kasan/quarantine.c @@ -144,13 +144,11 @@ static void *qlink_to_object(struct qlist_node *qlink, struct kmem_cache *cache) static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache) { void *object = qlink_to_object(qlink, cache); - struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object); unsigned long flags; if (IS_ENABLED(CONFIG_SLAB)) local_irq_save(flags); - alloc_info->state = KASAN_STATE_FREE; ___cache_free(cache, object, _THIS_IP_); if (IS_ENABLED(CONFIG_SLAB)) -- cgit v1.2.3