APPLIED: [SRU][N:hwe-6.17/N:hwe-6.17][PATCH 0/2] CVE-2026-43499

[Edoardo Canepa]

Applied to noble:linux/hwe-6.17-next. Thanks.

On 7/22/26 19:02, Cengiz Can via kernel-team wrote:
> https://ubuntu.com/security/CVE-2026-43499
>
> [ Impact ]
>
> remove_waiter() in the rtmutex slow path operated on "current" instead of
> the actual waiter task. When called for proxy-lock rollback in
> rt_mutex_start_proxy_lock() via futex_requeue(), waiter::task is not
> current, so the rbtree dequeue ran without holding the waiter's pi_lock and
> left the waiter's pi_blocked_on set. That dangling pointer is primed for a
> use-after-free, and rt_mutex_adjust_prio_chain() acts on the wrong top
> waiter. It is reachable locally through the futex requeue path.
>
> [ Fix ]
>
> noble/linux-hwe-6.17: clean cherry-pick
>
> [ Test Plan ]
>
> Build tested only (CBD).
>
> [ Where Problems Could Occur ]
>
> The change is in the core priority-inheritance rtmutex slow path
> (kernel/locking/rtmutex.c). A mistake here could affect PI correctness or
> lock ordering on futex requeue and PREEMPT_RT, but this is a clean pick of
> the upstream fix with no adaptation.
>
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