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From:   Andrey Konovalov <andreyknvl@google.com>
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Cc:     Kostya Serebryany <kcc@google.com>,
        Evgeniy Stepanov <eugenis@google.com>,
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        Andrey Konovalov <andreyknvl@google.com>
Subject: [PATCH v4 08/17] khwasan, arm64: fix up fault handling logic
Date:   Tue, 26 Jun 2018 15:15:18 +0200
Message-Id: <9f3e30f8144682c989bbf9fdac081501258a0b06.1530018818.git.andreyknvl@google.com>
In-Reply-To: <cover.1530018818.git.andreyknvl@google.com>
References: <cover.1530018818.git.andreyknvl@google.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

show_pte in arm64 fault handling relies on the fact that the top byte of
a kernel pointer is 0xff, which isn't always the case with KHWASAN enabled.
Reset the top byte.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 arch/arm64/mm/fault.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index b8eecc7b9531..b7b152783d54 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -32,6 +32,7 @@
 #include <linux/perf_event.h>
 #include <linux/preempt.h>
 #include <linux/hugetlb.h>
+#include <linux/kasan.h>
 
 #include <asm/bug.h>
 #include <asm/cmpxchg.h>
@@ -134,6 +135,8 @@ void show_pte(unsigned long addr)
 	pgd_t *pgdp;
 	pgd_t pgd;
 
+	addr = (unsigned long)khwasan_reset_tag((void *)addr);
+
 	if (addr < TASK_SIZE) {
 		/* TTBR0 */
 		mm = current->active_mm;
-- 
2.18.0.rc2.346.g013aa6912e-goog