linux-kernel - [PATCH v2 2/2] kasan, arm64: fix pointer tags in KASAN reports

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Message-Id: <3d9e6dece676e9da49d9913c78fd647db7dad552.1610652791.git.andreyknvl@google.com>
Date:   Thu, 14 Jan 2021 20:33:57 +0100
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Marco Elver <elver@...gle.com>
Cc:     Will Deacon <will.deacon@....com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Peter Collingbourne <pcc@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        kasan-dev@...glegroups.com, linux-arm-kernel@...ts.infradead.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH v2 2/2] kasan, arm64: fix pointer tags in KASAN reports

As of the "arm64: expose FAR_EL1 tag bits in siginfo" patch, the address
that is passed to report_tag_fault has pointer tags in the format of 0x0X,
while KASAN uses 0xFX format (note the difference in the top 4 bits).

Fix up the pointer tag before calling kasan_report.

Link: https://linux-review.googlesource.com/id/I9ced973866036d8679e8f4ae325de547eb969649
Fixes: dceec3ff7807 ("arm64: expose FAR_EL1 tag bits in siginfo")
Fixes: 4291e9ee6189 ("kasan, arm64: print report from tag fault handler")
Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
 arch/arm64/mm/fault.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 3c40da479899..a218f6f2fdc8 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -304,6 +304,8 @@ static void report_tag_fault(unsigned long addr, unsigned int esr,
 {
 	bool is_write  = ((esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT) != 0;
 
+	/* The format of KASAN tags is 0xF<x>. */
+	addr |= (0xF0UL << MTE_TAG_SHIFT);
 	/*
 	 * SAS bits aren't set for all faults reported in EL1, so we can't
 	 * find out access size.
-- 
2.30.0.284.gd98b1dd5eaa7-goog