[PATCH] arm64: fix wrong check of on_sdei_stack in nmi context

From: Wei Li <liwei391@huawei.com>
To: <catalin.marinas@arm.com>, <will.deacon@arm.com>,
	<mark.rutland@arm.com>,  <labbott@redhat.com>,
	<alex.popov@linux.com>, <james.morse@arm.com>
Cc: guohanjun@huawei.com, huawei.libin@huawei.com,
	linux-arm-kernel@lists.infradead.org, julien.thierry@arm.com
Subject: [PATCH] arm64: fix wrong check of on_sdei_stack in nmi context
Date: Mon, 1 Apr 2019 11:55:57 +0800	[thread overview]
Message-ID: <20190401035557.22191-1-liwei391@huawei.com> (raw)

When doing unwind_frame() in the context of pseudo nmi (need enable
CONFIG_ARM64_PSEUDO_NMI), reaching the botton of the stack (fp == 0,
pc != 0), function on_sdei_stack() will return true while the sdei acpi
table is not inited in fact. This will cause a "NULL pointer dereference"
oops when going on.

Signed-off-by: Wei Li <liwei391@huawei.com>
---
 arch/arm64/kernel/sdei.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm64/kernel/sdei.c b/arch/arm64/kernel/sdei.c
index 5ba4465e44f0..ea94cf8f9dc6 100644
--- a/arch/arm64/kernel/sdei.c
+++ b/arch/arm64/kernel/sdei.c
@@ -94,6 +94,9 @@ static bool on_sdei_normal_stack(unsigned long sp, struct stack_info *info)
 	unsigned long low = (unsigned long)raw_cpu_read(sdei_stack_normal_ptr);
 	unsigned long high = low + SDEI_STACK_SIZE;
 
+	if (!low)
+		return false;
+
 	if (sp < low || sp >= high)
 		return false;
 
@@ -111,6 +114,9 @@ static bool on_sdei_critical_stack(unsigned long sp, struct stack_info *info)
 	unsigned long low = (unsigned long)raw_cpu_read(sdei_stack_critical_ptr);
 	unsigned long high = low + SDEI_STACK_SIZE;
 
+	if (!low)
+		return false;
+
 	if (sp < low || sp >= high)
 		return false;
 
-- 
2.17.1


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