synclink: fix info leak in ioctl

The hdlcdev_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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/synclink.c

@@ -7866,6 +7866,7 @@ static int hdlcdev_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 					      HDLC_FLAG_TXC_TXCPIN | HDLC_FLAG_TXC_DPLL |
 					      HDLC_FLAG_TXC_BRG    | HDLC_FLAG_TXC_RXCPIN);
 
+		memset(&new_line, 0, sizeof(new_line));
 		switch (flags){
 		case (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_TXCPIN): new_line.clock_type = CLOCK_EXT; break;
 		case (HDLC_FLAG_RXC_BRG    | HDLC_FLAG_TXC_BRG):    new_line.clock_type = CLOCK_INT; break;

drivers/tty/synclinkmp.c

@@ -1766,6 +1766,7 @@ static int hdlcdev_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 					      HDLC_FLAG_TXC_TXCPIN | HDLC_FLAG_TXC_DPLL |
 					      HDLC_FLAG_TXC_BRG    | HDLC_FLAG_TXC_RXCPIN);
 
+		memset(&new_line, 0, sizeof(new_line));
 		switch (flags){
 		case (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_TXCPIN): new_line.clock_type = CLOCK_EXT; break;
 		case (HDLC_FLAG_RXC_BRG    | HDLC_FLAG_TXC_BRG):    new_line.clock_type = CLOCK_INT; break;