From 820a1e6e87ccaa6c0c77ac7d79d05beec3f8cb88 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox (Oracle) Date: Fri, 5 Nov 2021 13:35:53 -0700 Subject: kasan: fix tag for large allocations when using CONFIG_SLAB 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: 7f94ffbc4c6a ("kasan: add hooks implementation for tag-based mode") Signed-off-by: Matthew Wilcox (Oracle) Acked-by: Marco Elver Reviewed-by: Andrey Konovalov Cc: Andrey Ryabinin Cc: Alexander Potapenko Cc: Dmitry Vyukov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/kasan/common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 3e0999892c36..8428da2aaf17 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -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 -- cgit v1.2.3