hamradio/yam: fix info leak in ioctl

The yam_ioctl() code fails to initialise the cmd field
of the struct yamdrv_ioctl_cfg. Add an explicit memset(0)
before filling the structure to avoid the 4-byte info leak.
Signed-off-by: NSalva Peiró <speiro@ai2.upv.es>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/hamradio/yam.c

@@ -1057,6 +1057,7 @@ static int yam_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 		break;
 
 	case SIOCYAMGCFG:
+		memset(&yi, 0, sizeof(yi));
 		yi.cfg.mask = 0xffffffff;
 		yi.cfg.iobase = yp->iobase;
 		yi.cfg.irq = yp->irq;