[PATCH 4.19 54/99] arm64: fix wrong check of on_sdei_stack in nmi context

[Greg Kroah-Hartman]

[ Upstream commit 1c41860864c8ae0387ef7d44f0000e99cbb2e06d ]

When doing unwind_frame() in the context of pseudo nmi (need enable
CONFIG_ARM64_PSEUDO_NMI), reaching the bottom 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.

Reviewed-by: Julien Thierry <julien.thie...@arm.com>
Signed-off-by: Wei Li <liwei...@huawei.com>
Signed-off-by: Catalin Marinas <catalin.mari...@arm.com>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 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;
 
-- 
2.20.1