Patch "xen-netfront: avoid crashing on resume after a failure in talk_to_netback()" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

xen-netfront: avoid crashing on resume after a failure in talk_to_netback()

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
xen-netfront-avoid-crashing-on-resume-after-a-failure-in-talk_to_netback.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Vitaly Kuznetsov <[email protected]>
Date: Thu, 11 May 2017 13:58:06 +0200
Subject: xen-netfront: avoid crashing on resume after a failure in talk_to_netback()

From: Vitaly Kuznetsov <[email protected]>

commit d86b5672b1adb98b4cdd6fbf0224bbfb03db6e2e upstream.

Unavoidable crashes in netfront_resume() and netback_changed() after a previous fail in talk_to_netback() (e.g. when we fail to read MAC from xenstore) were discovered. The failure path in talk_to_netback() does unregister/free for netdev but we don't reset drvdata and we try accessing it after resume.

Fix the bug by removing the whole xen device completely with device_unregister(), this guarantees we won't have any calls into netfront after a failure.

---
 drivers/net/xen-netfront.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

@@ -1944,8 +1944,7 @@ abort_transaction_no_dev_fatal:
 	xennet_disconnect_backend(info);
 	xennet_destroy_queues(info);
  out:
-	unregister_netdev(info->netdev);
-	xennet_free_netdev(info->netdev);
+	device_unregister(&dev->dev);
 	return err;
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/xen-netfront-avoid-crashing-on-resume-after-a-failure-in-talk_to_netback.patch