From 34fae9c906ec93d7c783d17b365cf1b84db415ec Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Mon, 26 Dec 2016 22:58:20 +0100
Subject: x86/mce/AMD: Make the init code more robust

[ Upstream commit 0dad3a3014a0b9e72521ff44f17e0054f43dcdea ]

If mce_device_init() fails then the mce device pointer is NULL and the
AMD mce code happily dereferences it.

Add a sanity check.

Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Reported-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/kernel/cpu/mcheck/mce_amd.c | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'arch')

diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c b/arch/x86/kernel/cpu/mcheck/mce_amd.c
index 3dfca7b302dc..a5b47c1361a0 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_amd.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c
@@ -955,6 +955,9 @@ static int threshold_create_bank(unsigned int cpu, unsigned int bank)
 	const char *name = get_name(bank, NULL);
 	int err = 0;
 
+	if (!dev)
+		return -ENODEV;
+
 	if (is_shared_bank(bank)) {
 		nb = node_to_amd_nb(amd_get_nb_id(cpu));
 
-- 
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