USB: usbip: missing lock in stub down

Missing lock in sysfs operation when we want to close the connection in order
to check the status and send the down event in a safe way.
Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@redhat.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20221003091016.641900-1-jtornosm@redhat.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/usbip/stub_dev.c

@@ -118,6 +118,8 @@ static ssize_t usbip_sockfd_store(struct device *dev, struct device_attribute *a
 	} else {
 		dev_info(dev, "stub down\n");
 
+		mutex_lock(&sdev->ud.sysfs_lock);
+
 		spin_lock_irq(&sdev->ud.lock);
 		if (sdev->ud.status != SDEV_ST_USED)
 			goto err;