--- caf6e4d194696204fa41632e220369a2ca2876a7
+++ a08c8994c89d9975257f3658d3376b54cd222334
@@ -4164,6 +4164,8 @@ static int hdlcdev_ioctl(struct net_devi
 	if (cmd != SIOCWANDEV)
 		return hdlc_ioctl(dev, ifr, cmd);
 
+	memset(&new_line, 0, size);
+
 	switch(ifr->ifr_settings.type) {
 	case IF_GET_IFACE: /* return current sync_serial_settings */