| From 1d0cb4c8864addc362bae98e8ffa5500c87e1227 Mon Sep 17 00:00:00 2001 |
| From: Catalin Marinas <catalin.marinas@arm.com> |
| Date: Tue, 17 May 2022 10:35:32 +0100 |
| Subject: arm64: mte: Ensure the cleared tags are visible before setting the PTE |
| |
| From: Catalin Marinas <catalin.marinas@arm.com> |
| |
| 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> |
| --- |
| arch/arm64/kernel/mte.c | 3 +++ |
| 1 file changed, 3 insertions(+) |
| |
| --- a/arch/arm64/kernel/mte.c |
| +++ b/arch/arm64/kernel/mte.c |
| @@ -73,6 +73,9 @@ void mte_sync_tags(pte_t old_pte, pte_t |
| 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) |
