linux-kernel - [PATCH AUTOSEL for 4.15 053/189] ARM: 8740/1: NOMMU: Make sure we do not hold stale data in mem[] array

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Date:   Mon, 9 Apr 2018 00:17:27 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Vladimir Murzin <vladimir.murzin@....com>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.15 053/189] ARM: 8740/1: NOMMU: Make sure we do
 not hold stale data in mem[] array

From: Vladimir Murzin <vladimir.murzin@....com>

[ Upstream commit 636e645f1f2a5826beacd23548696f1655b0b5d8 ]

adjust_lowmem_bounds() called twice which can lead to stalled data
(i.e. subreg) value in mem[] array after the first call.

Zero out mem[] array before we allocate MPU regions for memory.

Fixes: 5c9d9a1b3a54 ("ARM: 8712/1: NOMMU: Use more MPU regions to cover memory")
Signed-off-by: Vladimir Murzin <vladimir.murzin@....com>
Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 arch/arm/mm/pmsa-v7.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm/mm/pmsa-v7.c b/arch/arm/mm/pmsa-v7.c
index 976df60ac426..f65c01fba9f4 100644
--- a/arch/arm/mm/pmsa-v7.c
+++ b/arch/arm/mm/pmsa-v7.c
@@ -6,6 +6,7 @@
 
 #include <linux/bitops.h>
 #include <linux/memblock.h>
+#include <linux/string.h>
 
 #include <asm/cacheflush.h>
 #include <asm/cp15.h>
@@ -296,6 +297,7 @@ void __init adjust_lowmem_bounds_mpu(void)
 		}
 	}
 
+	memset(mem, 0, sizeof(mem));
 	num = allocate_region(mem_start, specified_mem_size, mem_max_regions, mem);
 
 	for (i = 0; i < num; i++) {
-- 
2.15.1