usbdevfs: Correct amount of data copied to user in processcompl_compat

commit 2102e06a upstream.

iso data buffers may have holes in them if some packets were short, so for
iso urbs we should always copy the entire buffer, just like the regular
processcompl does.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/usb/core/devio.c

@@ -1555,10 +1555,14 @@ static int processcompl_compat(struct async *as, void __user * __user *arg)
 	void __user *addr = as->userurb;
 	unsigned int i;
 
-	if (as->userbuffer && urb->actual_length)
-		if (copy_to_user(as->userbuffer, urb->transfer_buffer,
-				 urb->actual_length))
+	if (as->userbuffer && urb->actual_length) {
+		if (urb->number_of_packets > 0)		/* Isochronous */
+			i = urb->transfer_buffer_length;
+		else					/* Non-Isoc */
+			i = urb->actual_length;
+		if (copy_to_user(as->userbuffer, urb->transfer_buffer, i))
 			return -EFAULT;
+	}
 	if (put_user(as->status, &userurb->status))
 		return -EFAULT;
 	if (put_user(urb->actual_length, &userurb->actual_length))