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>

diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c b/arch/x86/kernel/cpu/mcheck/mce_amd.c
index be121fb8d88d4f15fb03b5621dc59277663f1915..82e588f72992fc865d63ea55e6f786e309a2936a 100644 (file)
--- a/arch/x86/kernel/cpu/mcheck/mce_amd.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c
@@ -573,6 +573,9 @@ static int threshold_create_bank(unsigned int cpu, unsigned int bank)
        const char *name = th_names[bank];
        int err = 0;
 
+       if (!dev)
+               return -ENODEV;
+
        if (is_shared_bank(bank)) {
                nb = node_to_amd_nb(amd_get_nb_id(cpu));