USB: fix read vs. disconnect race in cytherm driver

the disconnect method of this driver set intfdata to NULL before
removing attribute files. The attributes' read methods will happily
follow the NULL pointer. Here's the correct ordering.

Signed-off-by : Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/misc/cytherm.c

@@ -399,14 +399,16 @@ static void cytherm_disconnect(struct usb_interface *interface)
 	struct usb_cytherm *dev;
 
 	dev = usb_get_intfdata (interface);
-	usb_set_intfdata (interface, NULL);
 
 	device_remove_file(&interface->dev, &dev_attr_brightness);
 	device_remove_file(&interface->dev, &dev_attr_temp);
 	device_remove_file(&interface->dev, &dev_attr_button);
 	device_remove_file(&interface->dev, &dev_attr_port0);
 	device_remove_file(&interface->dev, &dev_attr_port1);
 
+	/* first remove the files, then NULL the pointer */
+	usb_set_intfdata (interface, NULL);
+
 	usb_put_dev(dev->udev);
 
 	kfree(dev);