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authorCatalin Marinas <catalin.marinas@arm.com>2022-05-17 10:35:32 +0100
committerWill Deacon <will@kernel.org>2022-05-17 14:29:51 +0100
commit1d0cb4c8864addc362bae98e8ffa5500c87e1227 (patch)
treea86bef28c0094d659065a86755b5b14fe433fa24
parenteb3d8ea3e1f03f4b0b72d8f5ed9eb7c3165862e8 (diff)
arm64: mte: Ensure the cleared tags are visible before setting the PTE
As an optimisation, only pages mapped with PROT_MTE in user space have the MTE tags zeroed. This is done lazily at the set_pte_at() time via mte_sync_tags(). However, this function is missing a barrier and another CPU may see the PTE updated before the zeroed tags are visible. Add an smp_wmb() barrier if the mapping is Normal Tagged. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Fixes: 34bfeea4a9e9 ("arm64: mte: Clear the tags when a page is mapped in user-space with PROT_MTE") Cc: <stable@vger.kernel.org> # 5.10.x Reported-by: Vladimir Murzin <vladimir.murzin@arm.com> Cc: Will Deacon <will@kernel.org> Reviewed-by: Steven Price <steven.price@arm.com> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> Link: https://lore.kernel.org/r/20220517093532.127095-1-catalin.marinas@arm.com Signed-off-by: Will Deacon <will@kernel.org>
-rw-r--r--arch/arm64/kernel/mte.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
index 78b3e0f8e997..d502703e8373 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -76,6 +76,9 @@ void mte_sync_tags(pte_t old_pte, pte_t pte)
mte_sync_page_tags(page, old_pte, check_swap,
pte_is_tagged);
}
+
+ /* ensure the tags are visible before the PTE is set */
+ smp_wmb();
}
int memcmp_pages(struct page *page1, struct page *page2)