From: Catalin Marinas <catalin.marinas@arm.com> stable inclusion from stable-v5.10.118 commit 6013ef5f51e0861a904b74a694e621bb451fe7ae category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5L686 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 1d0cb4c8864addc362bae98e8ffa5500c87e1227 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Acked-by: Xie XiuQi <xiexiuqi@huawei.com> --- arch/arm64/kernel/mte.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c index 7a66a7d9c1ff..4a069f85bd91 100644 --- a/arch/arm64/kernel/mte.c +++ b/arch/arm64/kernel/mte.c @@ -45,6 +45,9 @@ void mte_sync_tags(pte_t *ptep, pte_t pte) if (!test_and_set_bit(PG_mte_tagged, &page->flags)) mte_sync_page_tags(page, ptep, check_swap); } + + /* ensure the tags are visible before the PTE is set */ + smp_wmb(); } int memcmp_pages(struct page *page1, struct page *page2) -- 2.20.1