On Wed, May 20, 2020 at 06:15:31PM +0300, Jere Leppänen wrote:
> Commit bdf6fa52f01b ("sctp: handle association restarts when the
> socket is closed.") starts shutdown when an association is restarted,
> if in SHUTDOWN-PENDING state and the socket is closed. However, the
> rationale stated in that commit applies also when in SHUTDOWN-SENT
> state - we don't want to move an association to ESTABLISHED state when
> the socket has been closed, because that results in an association
> that is unreachable from user space.
>
> The problem scenario:
>
> 1. Client crashes and/or restarts.
>
> 2. Server (using one-to-one socket) calls close(). SHUTDOWN is lost.
>
> 3. Client reconnects using the same addresses and ports.
>
> 4. Server's association is restarted. The association and the socket
> move to ESTABLISHED state, even though the server process has
> closed its descriptor.
>
> Also, after step 4 when the server process exits, some resources are
> leaked in an attempt to release the underlying inet sock structure in
> ESTABLISHED state:
>
> IPv4: Attempt to release TCP socket in state 1 00000000377288c7
>
> Fix by acting the same way as in SHUTDOWN-PENDING state. That is, if
> an association is restarted in SHUTDOWN-SENT state and the socket is
> closed, then start shutdown and don't move the association or the
> socket to ESTABLISHED state.
>
> Fixes: bdf6fa52f01b ("sctp: handle association restarts when the socket is closed.")
> Signed-off-by: Jere Leppänen <jere.leppanen@xxxxxxxxx>
> ---
> net/sctp/sm_statefuns.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
> index 26788f4a3b9e..e86620fbd90f 100644
> --- a/net/sctp/sm_statefuns.c
> +++ b/net/sctp/sm_statefuns.c
> @@ -1856,12 +1856,13 @@ static enum sctp_disposition sctp_sf_do_dupcook_a(
> /* Update the content of current association. */
> sctp_add_cmd_sf(commands, SCTP_CMD_UPDATE_ASSOC, SCTP_ASOC(new_asoc));
> sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
> - if (sctp_state(asoc, SHUTDOWN_PENDING) &&
> + if ((sctp_state(asoc, SHUTDOWN_PENDING) ||
> + sctp_state(asoc, SHUTDOWN_SENT)) &&
> (sctp_sstate(asoc->base.sk, CLOSING) ||
> sock_flag(asoc->base.sk, SOCK_DEAD))) {
> - /* if were currently in SHUTDOWN_PENDING, but the socket
> - * has been closed by user, don't transition to ESTABLISHED.
> - * Instead trigger SHUTDOWN bundled with COOKIE_ACK.
> + /* If the socket has been closed by user, don't
> + * transition to ESTABLISHED. Instead trigger SHUTDOWN
> + * bundled with COOKIE_ACK.
> */
> sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
> return sctp_sf_do_9_2_start_shutdown(net, ep, asoc,
>
> base-commit: 20a785aa52c82246055a089e55df9dac47d67da1
This last line is not standard, but git didn't complain about it here.
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>
