util: Prevent libvirtd crash from virNetDevOpenvswitchAddPort()

* src/util/virnetdevopenvswitch.c (virNetDevOpenvswitchAddPort): avoid libvirtd
crash due to derefing a NULL virtVlan->tag.

RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=852383

Signed-off-by: Alex Jia <ajia@redhat.com>

diff --git a/src/util/virnetdevopenvswitch.c b/src/util/virnetdevopenvswitch.c
index 601d79e6294383c2707b7a6404515c1807aceb37..b903ae4ee668d9ae83f27673313a3ef2e9d8e29c 100644 (file)
--- a/src/util/virnetdevopenvswitch.c
+++ b/src/util/virnetdevopenvswitch.c
@@ -99,7 +99,7 @@ int virNetDevOpenvswitchAddPort(const char *brname, const char *ifname,
                 virBufferAddLit(buf, ",");
                 virBufferAsprintf(buf, "%d", virtVlan->tag[i]);
             }
-        } else {
+        } else if (virtVlan->nTags) {
             virBufferAsprintf(buf, "tag=%d", virtVlan->tag[0]);
         }
     }