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kasan: fix tag for large allocations when using CONFIG_SLAB

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If an object is allocated on a tail page of a multi-page slab, kasan
will get the wrong tag because page->s_mem is NULL for tail pages.  I'm
not quite sure what the user-visible effect of this might be.

Link: https://lkml.kernel.org/r/20211001024105.3217339-1-willy@infradead.org
Fixes: 7f94ffbc4c ("kasan: add hooks implementation for tag-based mode")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Marco Elver <elver@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2021-11-05 13:35:53 -07:00 committed by Linus Torvalds
parent f70da745be
commit 820a1e6e87
1 changed files with 1 additions and 1 deletions
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2
mm/kasan/common.c
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@ -298,7 +298,7 @@ static inline u8 assign_tag(struct kmem_cache *cache,
/* For caches that either have a constructor or SLAB_TYPESAFE_BY_RCU: */
#ifdef CONFIG_SLAB
/* For SLAB assign tags based on the object index in the freelist. */
return (u8)obj_to_index(cache, virt_to_page(object), (void *)object);
return (u8)obj_to_index(cache, virt_to_head_page(object), (void *)object);
#else
/*
* For SLUB assign a random tag during slab creation, otherwise reuse