[PATCH v1 07/16] khwasan, arm64: fix up fault handling logic

From: Andrey Konovalov <andreyknvl@google.com>
To: "Andrey Ryabinin" <aryabinin@virtuozzo.com>,
	"Alexander Potapenko" <glider@google.com>,
	"Dmitry Vyukov" <dvyukov@google.com>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Will Deacon" <will.deacon@arm.com>,
	"Christopher Li" <sparse@chrisli.org>,
	"Christoph Lameter" <cl@linux.com>,
	"Pekka Enberg" <penberg@kernel.org>,
	"David Rientjes" <rientjes@google.com>,
	"Joonsoo Kim" <iamjoonsoo.kim@lge.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Masahiro Yamada" <yamada.masahiro@socionext.com>,
	"Michal Marek" <michal.lkml@markovi.net>,
	"Andrey Konovalov" <andreyknvl@google.com>,
	"Mark Rutland" <mark.rutland@arm.com>,
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	"Mel Gorman" <mgorman@suse.de>,
	"Pavel Tatashin" <pasha.tatashin@oracle.com>,
	"Tetsuo Handa" <penguin-kernel@I-love.SAKURA.ne.jp>,
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Cc: Kostya Serebryany <kcc@google.com>,
	Evgeniy Stepanov <eugenis@google.com>,
	Lee Smith <Lee.Smith@arm.com>,
	Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>,
	Jacob Bramley <Jacob.Bramley@arm.com>,
	Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>,
	Kees Cook <keescook@google.com>, Jann Horn <jannh@google.com>,
	Mark Brand <markbrand@google.com>,
	Chintan Pandya <cpandya@codeaurora.org>
Subject: [PATCH v1 07/16] khwasan, arm64: fix up fault handling logic
Date: Tue,  8 May 2018 19:20:53 +0200	[thread overview]
Message-ID: <a8771c5ec3469b68fbb510bda74aac4e42e49cab.1525798754.git.andreyknvl@google.com> (raw)
In-Reply-To: <cover.1525798753.git.andreyknvl@google.com>
In-Reply-To: <cover.1525798753.git.andreyknvl@google.com>

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 4165485e8b6e..e834fe76f5d2 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;
-- 
2.17.0.441.gb46fe60e1d-goog
