yam: use memdup_user

Use memdup_user() helper instead of open-coding to simplify the code.
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/hamradio/yam.c

@@ -976,12 +976,10 @@ static int yam_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 	case SIOCYAMSMCS:
 		if (netif_running(dev))
 			return -EINVAL;		/* Cannot change this parameter when up */
-		if ((ym = kmalloc(sizeof(struct yamdrv_ioctl_mcs), GFP_KERNEL)) == NULL)
-			return -ENOBUFS;
-		if (copy_from_user(ym, ifr->ifr_data, sizeof(struct yamdrv_ioctl_mcs))) {
-			kfree(ym);
-			return -EFAULT;
-		}
+		ym = memdup_user(ifr->ifr_data,
+				 sizeof(struct yamdrv_ioctl_mcs));
+		if (IS_ERR(ym))
+			return PTR_ERR(ym);
 		if (ym->bitrate > YAM_MAXBITRATE) {
 			kfree(ym);
 			return -EINVAL;