USB: race on disconnect in mdc800

I overlooked one. Setting the flag and killing the URBs must be under the lock
so that no URB is submitted after usb_kill_urb()
Signed-off-by: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/image/mdc800.c

@@ -565,11 +565,15 @@ static void mdc800_usb_disconnect (struct usb_interface *intf)
 
 		usb_deregister_dev(intf, &mdc800_class);
 
+		/* must be under lock to make sure no URB
+		   is submitted after usb_kill_urb() */
+		mutex_lock(&mdc800->io_lock);
 		mdc800->state=NOT_CONNECTED;
 
 		usb_kill_urb(mdc800->irq_urb);
 		usb_kill_urb(mdc800->write_urb);
 		usb_kill_urb(mdc800->download_urb);
+		mutex_unlock(&mdc800->io_lock);
 
 		mdc800->dev = NULL;
 		usb_set_intfdata(intf, NULL);