Re: [PATCH 6.12.y 0/2] sched/psi: fix race in pressure_write (CVE-2026-52991)

[Sasha Levin]

On Wed, Jul 15, 2026 at 04:32:43PM +0800, Philo Lu wrote:
> Backport of the CVE-2026-52991 fix.
>
>   1/2 (94a4acfec146) clear of->priv on release, turning the UAF into an
>       easier-to-detect NULL deref.
>   2/2 (a5b98009f16d, the CVE fix) extend cgroup_mutex to cover all
>       of->priv accesses, read ctx after taking the kn lock, and NULL-check
>       of->priv. It depends on 1/2 as discussed in [0].

I'm holding off on this series (and the 6.6.y/6.1.y ones) for now: a5b98009f16d
moves the psi trigger write path under cgroup_mutex, which means the psimon
kthread gets created while holding cgroup_mutex and introduces a deadlock risk.

Tejun has a follow-up fix for that which is in the cgroup tree but hasn't
reached mainline yet. Once it lands, I'll queue your series together with it on
all three branches.

-- 
Thanks,
Sasha