Re: [PATCH 6.12.y] mptcp: pm: ADD_ADDR rtx: free sk if last

[Matthieu Baerts <matttbe@kernel.org>]

Hi Sasha,

On 19/05/2026 00:40, Sasha Levin wrote:
> From: "Matthieu Baerts (NGI0)" <matttbe@kernel.org>
> 
> [ Upstream commit b7b9a461569734d33d3259d58d2507adfac107ed ]
> 
> When an ADD_ADDR is retransmitted, the sk is held in sk_reset_timer(),
> and released at the end.
> 
> If at that moment, it was the last reference being held, the sk would
> not be freed. sock_put() should then be called instead of __sock_put().
> 
> But that's not enough: if it is the last reference, sock_put() will call
> sk_free(), which will end up calling sk_stop_timer_sync() on the same
> timer, and waiting indefinitely to finish. So it is needed to mark that
> the timer is done at the end of the timer handler when it has not been
> rescheduled, not to call sk_stop_timer_sync() on "itself".
> 
> Fixes: 00cfd77b9063 ("mptcp: retransmit ADD_ADDR when timeout")
> Cc: stable@vger.kernel.org
> Reviewed-by: Mat Martineau <martineau@kernel.org>
> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
> Link: https://patch.msgid.link/20260505-net-mptcp-pm-fixes-7-1-rc3-v1-5-fca8091060a4@kernel.org
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> Signed-off-by: Sasha Levin <sashal@kernel.org>

I suspect that here as well, you got more conflicts because this patch
is taken individually, and not applied after others you previously sent,
like "mptcp: pm: ADD_ADDR rtx: fix potential data-race" and "mptcp: pm:
ADD_ADDR rtx: always decrease sk refcount".

In other words, this resolution is not correct, and the resolution
should be easier if each patch sent previously is applied before sending
the next ones.

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.