x86: Fixed NULL function pointer dereference in AMD microcode patch loader.

Dereference took place in code part responsible for manual installation
of microcode patches through /dev/cpu/microcode.

Signed-off-by: Peter Oruba <peter.oruba@amd.com>
Cc: Peter Oruba <peter.oruba@amd.com>
Cc: Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 1 deletions

diff --git a/arch/x86/kernel/microcode.c b/arch/x86/kernel/microcode.c
index 39961bb83293..ad136ad99cb3 100644
--- a/arch/x86/kernel/microcode.c
+++ b/arch/x86/kernel/microcode.c
@@ -127,7 +127,8 @@ static int do_microcode_update(void)
         old = current->cpus_allowed;
 
         while ((cursor = microcode_ops->get_next_ucode(&new_mc, cursor)) > 0) {
-                error = microcode_ops->microcode_sanity_check(new_mc);
+                if (microcode_ops->microcode_sanity_check != NULL)
+                        error = microcode_ops->microcode_sanity_check(new_mc);
                 if (error)
                         goto out;
                 /*