wan/fsl_ucc_hdlc: info leak in uhdlc_ioctl()

There is a 2 byte struct whole after line.loopback so we need to clear
that out to avoid disclosing stack information.

Fixes: c19b6d246a35 ('drivers/net: support hdlc function for QE-UCC')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wan/fsl_ucc_hdlc.c

@@ -635,9 +635,8 @@ static int uhdlc_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 = priv->clocking;
-		line.clock_rate = 0;
-		line.loopback = 0;
 
 		if (copy_to_user(ifr->ifr_settings.ifs_ifsu.sync, &line, size))
 			return -EFAULT;