(get_interface_list) Properly handle an interface not appearing in dmesg

src/etc/inc/util.inc

@@ -948,12 +948,13 @@ function get_interface_list($only_active = false)
         }
 
         $dmesg_arr = array();
+        $toput['dmesg'] = null;
         exec("/sbin/dmesg |grep $ifname", $dmesg_arr);
+        if (count($dmesg_arr) > 0) {
             preg_match_all("/<(.*?)>/i", $dmesg_arr[0], $dmesg);
             if (isset($dmesg[1][0])) {
                 $toput['dmesg'] = $dmesg[1][0];
-        } else {
-            $toput['dmesg'] = null;
+            }
         }
 
         $iflist[$ifname] = $toput;