USB: cypress_cy7c63: race disconnect/sysfs read-write leading to following NULL pointer

this driver sets intfdata to NULL while it still can be read and happily followed.
Signed-off-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/misc/cypress_cy7c63.c

@@ -246,11 +246,13 @@ static void cypress_disconnect(struct usb_interface *interface)
 	struct cypress *dev;
 
 	dev = usb_get_intfdata(interface);
-	usb_set_intfdata(interface, NULL);
 
 	/* remove device attribute files */
 	device_remove_file(&interface->dev, &dev_attr_port0);
 	device_remove_file(&interface->dev, &dev_attr_port1);
+	/* the intfdata can be set to NULL only after the
+	 * device files have been removed */
+	usb_set_intfdata(interface, NULL);
 
 	usb_put_dev(dev->udev);