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| author | Catalin Marinas <catalin.marinas@arm.com> | 2022-06-10 18:21:38 +0300 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2022-07-07 12:48:37 +0300 |
| commit | ed0a6d1d973e9763989b44913ae1bd2a5d5d5777 (patch) | |
| tree | 59525214e06904d5cc0c020fea1e4e129d6172d7 | |
| parent | a111daf0c53ae91e71fd2bfe7497862d14132e3e (diff) | |
| download | linux-ed0a6d1d973e9763989b44913ae1bd2a5d5d5777.tar.xz | |
mm: kasan: Ensure the tags are visible before the tag in page->flags
__kasan_unpoison_pages() colours the memory with a random tag and stores
it in page->flags in order to re-create the tagged pointer via
page_to_virt() later. When the tag from the page->flags is read, ensure
that the in-memory tags are already visible by re-ordering the
page_kasan_tag_set() after kasan_unpoison(). The former already has
barriers in place through try_cmpxchg(). On the reader side, the order
is ensured by the address dependency between page->flags and the memory
access.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lore.kernel.org/r/20220610152141.2148929-2-catalin.marinas@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
| -rw-r--r-- | mm/kasan/common.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/kasan/common.c b/mm/kasan/common.c index c40c0e7b3b5f..78be2beb7453 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -108,9 +108,10 @@ void __kasan_unpoison_pages(struct page *page, unsigned int order, bool init) return; tag = kasan_random_tag(); + kasan_unpoison(set_tag(page_address(page), tag), + PAGE_SIZE << order, init); for (i = 0; i < (1 << order); i++) page_kasan_tag_set(page + i, tag); - kasan_unpoison(page_address(page), PAGE_SIZE << order, init); } void __kasan_poison_pages(struct page *page, unsigned int order, bool init) |