wanxl: fix info leak in ioctl

The wanxl_ioctl() code fails to initialize the two padding bytes of
struct sync_serial_settings after the ->loopback member. Add an explicit
memset(0) before filling the structure to avoid the info leak.
Signed-off-by: Salva Peiró <speiro@ai2.upv.es>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wan/wanxl.c

@@ -355,6 +355,7 @@ static int wanxl_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 			ifr->ifr_settings.size = size; /* data size wanted */
 			return -ENOBUFS;
 		}
+		memset(&line, 0, sizeof(line));
 		line.clock_type = get_status(port)->clocking;
 		line.clock_rate = 0;
 		line.loopback = 0;