USB: iowarrior: use memdup_user

Use memdup_user() helper instead of open-coding to simplify the code.
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Reviewed-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/misc/iowarrior.c

@@ -368,14 +368,9 @@ static ssize_t iowarrior_write(struct file *file,
 	case USB_DEVICE_ID_CODEMERCS_IOWPV2:
 	case USB_DEVICE_ID_CODEMERCS_IOW40:
 		/* IOW24 and IOW40 use a synchronous call */
-		buf = kmalloc(count, GFP_KERNEL);
-		if (!buf) {
-			retval = -ENOMEM;
-			goto exit;
-		}
-		if (copy_from_user(buf, user_buffer, count)) {
-			retval = -EFAULT;
-			kfree(buf);
+		buf = memdup_user(user_buffer, count);
+		if (IS_ERR(buf)) {
+			retval = PTR_ERR(buf);
 			goto exit;
 		}
 		retval = usb_set_report(dev->interface, 2, 0, buf, count);