s390/cio: return -EFAULT if copy_to_user() fails

commit d9c48a9 upstream.

Fixes: 120e214 ("vfio: ccw: realize VFIO_DEVICE_G(S)ET_IRQ_INFO ioctls")
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/s390/cio/vfio_ccw_ops.c

@@ -582,7 +582,7 @@ static ssize_t vfio_ccw_mdev_ioctl(struct mdev_device *mdev,
 		if (info.count == -1)
 			return -EINVAL;
 
-		return copy_to_user((void __user *)arg, &info, minsz);
+		return copy_to_user((void __user *)arg, &info, minsz) ? -EFAULT : 0;
 	}
 	case VFIO_DEVICE_SET_IRQS:
 	{