x86/mce/AMD: Make the init code more robust

KAGA-KOKO · torvalds · commit 0dad3a3014a0 · 2016-12-26T17:30:24.000-08:00
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 &lt;markus@trippelsdorf.de&gt;
Reported-by: Boris Ostrovsky &lt;boris.ostrovsky@oracle.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c b/arch/x86/kernel/cpu/mcheck/mce_amd.c
@@ -1182,6 +1182,9 @@ 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));
 
