Re: Backport xfrm race condition fix to stable kernel version 6.6.y

Re: Backport xfrm race condition fix to stable kernel version 6.6.y

[Sasha Levin]

On Mon, Aug 17, 2026 at 03:10:09PM -0700, Tahera Fahimi wrote:
> I am writing to request the backport of the following patch to stable kernel versions 6.6.y,
> addressing CVE-2026-31516.
>
> Patch to Apply:
>     Subject: xfrm: prevent policy_hthresh.work from racing with netns teardown
>     Commit ID: 29fe3a61bcdce398ee3955101c39f89c01a8a77e

This one is already in 7.1.y, 6.18.y and 6.12.y, but it can't be taken
as-is on 6.6 and older: the line it adds calls disable_work_sync(), which
only exists from v6.10 onwards, 86898fa6b8cd ("workqueue: Implement
disable/enable for (delayed) work items"). The cherry-pick applies
cleanly and then fails to build.

Substituting cancel_work_sync() compiles, but it drops the re-queue
prevention the commit exists to add, and I'd rather not make that
substitution silently on a CVE fix.

Could you send a tested backport for the pre-6.10 trees (6.6, 6.1, 5.15,
5.10)? Netdev folks Cc'd in case they'd rather do it.

-- 
Thanks,
Sasha