On Tue, Jun 27, 2023 at 03:25:57PM +0200, Matthieu Baerts wrote:
> From: Paolo Abeni <pabeni@xxxxxxxxxx>
>
> commit 81c1d029016001f994ce1c46849c5e9900d8eab8 upstream.
>
> An orphaned msk releases the used resources via the worker,
> when the latter first see the msk in CLOSED status.
>
> If the msk status transitions to TCP_CLOSE in the release callback
> invoked by the worker's final release_sock(), such instance of the
> workqueue will not take any action.
>
> Additionally the MPTCP code prevents scheduling the worker once the
> socket reaches the CLOSE status: such msk resources will be leaked.
>
> The only code path that can trigger the above scenario is the
> __mptcp_check_send_data_fin() in fallback mode.
>
> Address the issue removing the special handling of fallback socket
> in __mptcp_check_send_data_fin(), consolidating the state machine
> for fallback and non fallback socket.
>
> Since non-fallback sockets do not send and do not receive data_fin,
> the mptcp code can update the msk internal status to match the next
> step in the SM every time data fin (ack) should be generated or
> received.
>
> As a consequence we can remove a bunch of checks for fallback from
> the fastpath.
>
> Fixes: 6e628cd3a8f7 ("mptcp: use mptcp release_cb for delayed tasks")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
> Reviewed-by: Mat Martineau <martineau@xxxxxxxxxx>
> Signed-off-by: Matthieu Baerts <matthieu.baerts@xxxxxxxxxxxx>
> Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
> Signed-off-by: Matthieu Baerts <matthieu.baerts@xxxxxxxxxxxx>
> ---
> Conflicting with:
> - 0522b424c4c2 ("mptcp: add do_check_data_fin to replace copied")
> - 3e5014909b56 ("mptcp: cleanup MPJ subflow list handling")
>
> I took the new modifications but leaving the old variable name for
> "copied" instead of "do_check_data_fin" and the calls to
> __mptcp_flush_join_list()
>
> Applied on top of d2efde0d1c2e ("Linux 5.15.119-rc1").
>
> Signed-off-by: Matthieu Baerts <matthieu.baerts@xxxxxxxxxxxx>
All backports now queued up, thanks.
greg k-h
