usbip: fix error handling in stub_probe()

If usb_hub_claim_port() fails, no resources are deallocated and
if stub_add_files() fails, port is not released.

The patch fixes these issues and rearranges error handling code.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <[e-mail]>
Acked-by: Valentina Manea <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/usbip/stub_dev.c

···
 {
 	struct stub_device *sdev = NULL;
 	const char *udev_busid = dev_name(&udev->dev);
-	int err = 0;
 	struct bus_id_priv *busid_priv;
 	int rc;
 
···
 			(struct usb_dev_state *) udev);
 	if (rc) {
 		dev_dbg(&udev->dev, "unable to claim port\n");
-		return rc;
+		goto err_port;
 	}
 
-	err = stub_add_files(&udev->dev);
-	if (err) {
+	rc = stub_add_files(&udev->dev);
+	if (rc) {
 		dev_err(&udev->dev, "stub_add_files for %s\n", udev_busid);
-		dev_set_drvdata(&udev->dev, NULL);
-		usb_put_dev(udev);
-		kthread_stop_put(sdev->ud.eh);
-
-		busid_priv->sdev = NULL;
-		stub_device_free(sdev);
-		return err;
+		goto err_files;
 	}
 	busid_priv->status = STUB_BUSID_ALLOC;
 
 	return 0;
+err_files:
+	usb_hub_release_port(udev->parent, udev->portnum,
+			     (struct usb_dev_state *) udev);
+err_port:
+	dev_set_drvdata(&udev->dev, NULL);
+	usb_put_dev(udev);
+	kthread_stop_put(sdev->ud.eh);
+
+	busid_priv->sdev = NULL;
+	stub_device_free(sdev);
+	return rc;
 }
 
 static void shutdown_busid(struct bus_id_priv *busid_priv)