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authorPeter Collingbourne <pcc@google.com>2022-01-30 00:41:14 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-01-30 10:56:58 +0300
commit27fe73394a1c6d0b07fa4d95f1bca116d1cc66e9 (patch)
tree1667b65ac52ebb8bc51f6e9d9e9db259220f7fa5 /include
parent09c6304e38e440b93a9ebf3f3cf75cd6cb529f91 (diff)
downloadlinux-27fe73394a1c6d0b07fa4d95f1bca116d1cc66e9.tar.xz
mm, kasan: use compare-exchange operation to set KASAN page tag
It has been reported that the tag setting operation on newly-allocated pages can cause the page flags to be corrupted when performed concurrently with other flag updates as a result of the use of non-atomic operations. Fix the problem by using a compare-exchange loop to update the tag. Link: https://lkml.kernel.org/r/20220120020148.1632253-1-pcc@google.com Link: https://linux-review.googlesource.com/id/I456b24a2b9067d93968d43b4bb3351c0cec63101 Fixes: 2813b9c02962 ("kasan, mm, arm64: tag non slab memory allocated via pagealloc") Signed-off-by: Peter Collingbourne <pcc@google.com> Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/mm.h17
1 files changed, 12 insertions, 5 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index e1a84b1e6787..213cc569b192 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1506,11 +1506,18 @@ static inline u8 page_kasan_tag(const struct page *page)
static inline void page_kasan_tag_set(struct page *page, u8 tag)
{
- if (kasan_enabled()) {
- tag ^= 0xff;
- page->flags &= ~(KASAN_TAG_MASK << KASAN_TAG_PGSHIFT);
- page->flags |= (tag & KASAN_TAG_MASK) << KASAN_TAG_PGSHIFT;
- }
+ unsigned long old_flags, flags;
+
+ if (!kasan_enabled())
+ return;
+
+ tag ^= 0xff;
+ old_flags = READ_ONCE(page->flags);
+ do {
+ flags = old_flags;
+ flags &= ~(KASAN_TAG_MASK << KASAN_TAG_PGSHIFT);
+ flags |= (tag & KASAN_TAG_MASK) << KASAN_TAG_PGSHIFT;
+ } while (unlikely(!try_cmpxchg(&page->flags, &old_flags, flags)));
}
static inline void page_kasan_tag_reset(struct page *page)