Re: [PATCH net] sctp: fix addr_wq_timer race in sctp_free_addr_wq()

On Tue, Jul 21, 2026 at 5:02=E2=80=AFPM Jakub Kicinski <[email protected]> wr=
ote:
>
> On Fri, 10 Jul 2026 14:23:43 -0400 Xin Long wrote:
> > sctp_free_addr_wq() previously removed addr_wq_timer using timer_delete=
()
> > while holding addr_wq_lock. However, timer_delete() does not guarantee =
that
> > a currently running timer handler has completed.
> >
> > This allows a race with sctp_addr_wq_timeout_handler(), where the handl=
er
> > may still run after addr_waitq has been freed, acquire addr_wq_lock, an=
d
> > access freed memory, leading to a use-after-free.
> >
> > Fix this by calling timer_shutdown_sync() before taking addr_wq_lock.  =
This
> > guarantees that any in-flight timer handler has finished and prevents t=
he
> > timer from being re-armed during teardown, making subsequent cleanup sa=
fe.
>
> This version did not apply when it was posted (IDK if it applies now)
> Please rebase and repost if it's still needed?
You already applied this one:

https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=
=3D976c19de0f22a857ba0112f39635f8fd7a257568

I think I accidently posted this one twice, sorry for the confusion.

We can drop this dup one.

Thanks.