Subject: Re: [PATCH v2] llc: Fix race between sock_orphan() and timer callback in llc_sk_free()

From: Jakub Kicinski <[email-masked]>
Date: Tue, 2 Jun 2026 13:30:02 -0700

On Fri, 29 May 2026 02:00:59 +0000 Jiakai Xu wrote:
> In llc_ui_release(), sock_orphan() was called before llc_sk_free()
> stopped all LLC timers. A pending timer callback
> (llc_conn_ack_tmr_cb()->llc_process_tmr_ev()->llc_conn_state_process())
> could fire between these two operations and dereference the
> NULL sk->sk_socket that sock_orphan() sets, causing a kernel
> page fault.
> 
> Fix the race by moving sock_orphan() into llc_sk_free(), after
> llc_sk_stop_all_timers() has completed. This guarantees that
> all timers are stopped before the socket is orphaned, eliminating
> the window for the race.

Sashiko points out that there's more issues if the timer runs after
llc_ui_release(). Can you reliably reproduce this? Have you checked
that this change is sufficient? Sashiko says that llc->dev may
disappear even tho we don't clear that pointer in _release().
-- 
pw-bot: cr