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authorCatalin Marinas <catalin.marinas@arm.com>2022-06-10 17:21:38 +0200
committerWill Deacon <will@kernel.org>2022-07-07 11:48:37 +0200
commited0a6d1d973e9763989b44913ae1bd2a5d5d5777 (patch)
tree59525214e06904d5cc0c020fea1e4e129d6172d7 /mm
parentLinux 5.19-rc3 (diff)
downloadlinux-ed0a6d1d973e9763989b44913ae1bd2a5d5d5777.tar.xz
linux-ed0a6d1d973e9763989b44913ae1bd2a5d5d5777.zip
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>
Diffstat (limited to 'mm')
-rw-r--r--mm/kasan/common.c3
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)