USB: cdc-wdm: fix memory leak

cleanup() is not called if the last close() comes after
disconnect(). That leads to a memory leak. Rectified
by checking for an earlier disconnect() in release()

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/class/cdc-wdm.c

@@ -622,6 +622,8 @@ static int wdm_release(struct inode *inode, struct file *file)
 		kill_urbs(desc);
 		if (!test_bit(WDM_DISCONNECTING, &desc->flags))
 			desc->manage_power(desc->intf, 0);
+		else
+			cleanup(desc);
 	}
 	mutex_unlock(&wdm_mutex);
 	return 0;