From 51dedad06b5f6c3eea7ec1069631b1ef7796912a Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Wed, 20 Feb 2019 22:20:28 -0800 Subject: [PATCH] kasan, slab: make freelist stored without tags Similarly to "kasan, slub: move kasan_poison_slab hook before page_address", move kasan_poison_slab() before alloc_slabmgmt(), which calls page_address(), to make page_address() return value to be non-tagged. This, combined with calling kasan_reset_tag() for off-slab slab management object, leads to freelist being stored non-tagged. Link: http://lkml.kernel.org/r/dfb53b44a4d00de3879a05a9f04c1f55e584f7a1.1550602886.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Tested-by: Qian Cai Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgeniy Stepanov Cc: Kostya Serebryany Cc: Vincenzo Frascino Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/slab.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/mm/slab.c b/mm/slab.c index c84458281a88..4ad95fcb1686 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -2359,7 +2359,7 @@ static void *alloc_slabmgmt(struct kmem_cache *cachep, void *freelist; void *addr = page_address(page); - page->s_mem = kasan_reset_tag(addr) + colour_off; + page->s_mem = addr + colour_off; page->active = 0; if (OBJFREELIST_SLAB(cachep)) @@ -2368,6 +2368,7 @@ static void *alloc_slabmgmt(struct kmem_cache *cachep, /* Slab management obj is off-slab. */ freelist = kmem_cache_alloc_node(cachep->freelist_cache, local_flags, nodeid); + freelist = kasan_reset_tag(freelist); if (!freelist) return NULL; } else { @@ -2681,6 +2682,13 @@ static struct page *cache_grow_begin(struct kmem_cache *cachep, offset *= cachep->colour_off; + /* + * Call kasan_poison_slab() before calling alloc_slabmgmt(), so + * page_address() in the latter returns a non-tagged pointer, + * as it should be for slab pages. + */ + kasan_poison_slab(page); + /* Get slab management. */ freelist = alloc_slabmgmt(cachep, page, offset, local_flags & ~GFP_CONSTRAINT_MASK, page_node); @@ -2689,7 +2697,6 @@ static struct page *cache_grow_begin(struct kmem_cache *cachep, slab_map_pages(cachep, page, freelist); - kasan_poison_slab(page); cache_init_objs(cachep, page); if (gfpflags_allow_blocking(local_flags))