xfrm interface: fix oops when deleting a x-netns interface

[Nicolas Dichtel]

[Impact]

When a netns is removed, it may corrupt x-netns xfrm interfaces that have their link part in this netns. It will later trigger an oops when those interfaces are removed.

This problem has been fixed in the upstream commit c95c5f58b35e ("xfrm interface: fix oops when deleting a x-netns interface"): https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c95c5f58b35e

[Test Case]

The steps to reproduce the oops is explained in the commit log of the upstream patch.

[Regression Potential]

The patch affects only the xfrm interface driver, more precisely, the deletion part. Thus, the potential regressions are limited to this area.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1881907

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Po-Hsu Lin (cypressyew)]

This patch can be found in D/E/F via stable update.

Disco - https://kernel.ubuntu.com/git/ubuntu/ubuntu-disco.git/commit/?h=master-next&id=453b92536f98dd855d268e3f7d75712d7c0fe2c7

Eoan - https://kernel.ubuntu.com/git/ubuntu/ubuntu-eoan.git/commit/?h=master-next&id=4494b72f82ea78b42b6c5a1f7aadc87d76f8ab1f

Focal - https://kernel.ubuntu.com/git/ubuntu/ubuntu-focal.git/commit/?h=master-next&id=9e6fe88b577ea8df133a98d1b6d6f463624a59b9

It seems the commit that cause this regression does not exist in Bionic.

I will mark this one as duplicated for stable update tracking bug.
Thanks.