| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.7 090/141] mm, kasan: account for object redzone in SLUBs nearest_obj() | Date | Thu, 6 Oct 2016 10:28:46 +0200 |
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4.7-stable review patch. If anyone has any objections, please let me know.
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From: Alexander Potapenko <glider@google.com>
commit c146a2b98eb5898eb0fab15a332257a4102ecae9 upstream.
When looking up the nearest SLUB object for a given address, correctly calculate its offset if SLAB_RED_ZONE is enabled for that cache.
Previously, when KASAN had detected an error on an object from a cache with SLAB_RED_ZONE set, the actual start address of the object was miscalculated, which led to random stacks having been reported.
When looking up the nearest SLUB object for a given address, correctly calculate its offset if SLAB_RED_ZONE is enabled for that cache.
Fixes: 7ed2f9e663854db ("mm, kasan: SLAB support") Link: http://lkml.kernel.org/r/1468347165-41906-2-git-send-email-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <adech.fo@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Steven Rostedt (Red Hat) <rostedt@goodmis.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Kuthonuzo Luruo <kuthonuzo.luruo@hpe.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- include/linux/slub_def.h | 10 ++++++---- mm/slub.c | 2 +- 2 files changed, 7 insertions(+), 5 deletions(-)
--- a/include/linux/slub_def.h +++ b/include/linux/slub_def.h @@ -114,15 +114,17 @@ static inline void sysfs_slab_remove(str void object_err(struct kmem_cache *s, struct page *page, u8 *object, char *reason); +void *fixup_red_left(struct kmem_cache *s, void *p); + static inline void *nearest_obj(struct kmem_cache *cache, struct page *page, void *x) { void *object = x - (x - page_address(page)) % cache->size; void *last_object = page_address(page) + (page->objects - 1) * cache->size; - if (unlikely(object > last_object)) - return last_object; - else - return object; + void *result = (unlikely(object > last_object)) ? last_object : object; + + result = fixup_red_left(cache, result); + return result; } #endif /* _LINUX_SLUB_DEF_H */ --- a/mm/slub.c +++ b/mm/slub.c @@ -124,7 +124,7 @@ static inline int kmem_cache_debug(struc #endif } -static inline void *fixup_red_left(struct kmem_cache *s, void *p) +inline void *fixup_red_left(struct kmem_cache *s, void *p) { if (kmem_cache_debug(s) && s->flags & SLAB_RED_ZONE) p += s->red_left_pad;
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