[PATCH v8 1/3] mm, kasan: account for object redzone in SLUB's nearest_obj()
From: Alexander Potapenko <glider@google.com>
Date: 2016-07-28 15:31:58
Also in:
lkml
Subsystem:
memory management, slab allocator, the rest · Maintainers:
Andrew Morton, Vlastimil Babka, Harry Yoo, Linus Torvalds
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.
Fixes: 7ed2f9e663854db ("mm, kasan: SLAB support")
Signed-off-by: Alexander Potapenko <glider@google.com>
---
v8: - Updated the patch description
---
include/linux/slub_def.h | 10 ++++++----
mm/slub.c | 2 +-
2 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 5624c1f..cf501cf 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h@@ -119,15 +119,17 @@ static inline void sysfs_slab_remove(struct kmem_cache *s) 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 */
diff --git a/mm/slub.c b/mm/slub.c
index f9da871..1cdde1a 100644
--- a/mm/slub.c
+++ b/mm/slub.c@@ -124,7 +124,7 @@ static inline int kmem_cache_debug(struct kmem_cache *s) #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;
--
2.8.0.rc3.226.g39d4020
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