From 932f26d9d8825261c5a8c78b113efb6cb2ed2036 Mon Sep 17 00:00:00 2001
From: Chao Gao <chao.gao@intel.com>
Date: Fri, 30 Aug 2019 10:22:55 +0200
Subject: [PATCH] x86/ucode/AMD: make freeing of old ucode conditional

It is certain to be NULL at least the first time through.

Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---
 xen/arch/x86/microcode_amd.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/microcode_amd.c b/xen/arch/x86/microcode_amd.c
index 306978457b..9b743307c4 100644
--- a/xen/arch/x86/microcode_amd.c
+++ b/xen/arch/x86/microcode_amd.c
@@ -552,9 +552,12 @@ static int cpu_request_microcode(unsigned int cpu, const void *buf,
         mc_old = mc_amd;
     }
 
-    xfree(mc_old->mpb);
-    xfree(mc_old->equiv_cpu_table);
-    xfree(mc_old);
+    if ( mc_old )
+    {
+        xfree(mc_old->mpb);
+        xfree(mc_old->equiv_cpu_table);
+        xfree(mc_old);
+    }
 
   out:
 #if CONFIG_HVM
-- 
2.30.2