Description: defer event channel bucket pointer store until after XSM checks
 Otherwise a dangling pointer can be left, which would cause subsequent
 memory corruption as soon as the space got re-allocated for some other
 purpose.
From: Jan Beulich <jbeulich@suse.com>
Origin: upstream
Id: CVE-2013-1920 XSA-47
---
--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -140,7 +140,6 @@ static int get_free_port(struct domain *
     chn = xzalloc_array(struct evtchn, EVTCHNS_PER_BUCKET);
     if ( unlikely(chn == NULL) )
         return -ENOMEM;
-    bucket_from_port(d, port) = chn;
 
     for ( i = 0; i < EVTCHNS_PER_BUCKET; i++ )
     {
@@ -153,6 +152,8 @@ static int get_free_port(struct domain *
         }
     }
 
+    bucket_from_port(d, port) = chn;
+
     return port;
 }
 
