linux-kernel - [PATCH] arm64: mm: reset address tag set by kasan sw tagging

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Message-Id: <1591787384-5823-1-git-send-email-sthombre@codeaurora.org>
Date:   Wed, 10 Jun 2020 16:39:44 +0530
From:   Shyam Thombre <sthombre@...eaurora.org>
To:     catalin.marinas@....com, will.deacon@....com,
        ard.biesheuvel@....com, mark.rutland@....com,
        anshuman.khandual@....com, sashal@...nel.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Shyam Thombre <sthombre@...eaurora.org>
Subject: [PATCH] arm64: mm: reset address tag set by kasan sw tagging

KASAN sw tagging sets a random tag of 8 bits in the top byte of the pointer
returned by the memory allocating functions. So for the functions unaware
of this change, the top 8 bits of the address must be reset which is done
by the function arch_kasan_reset_tag().

Signed-off-by: Shyam Thombre <sthombre@...eaurora.org>
---
 arch/arm64/mm/mmu.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index e7fbc62..eae7655 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -723,6 +723,7 @@ int kern_addr_valid(unsigned long addr)
 	pmd_t *pmdp, pmd;
 	pte_t *ptep, pte;
 
+	addr = arch_kasan_reset_tag(addr);
 	if ((((long)addr) >> VA_BITS) != -1UL)
 		return 0;
 
-- 
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