From: Qing Luo In sctp_sf_do_6_3_3_rtx(), the zero window detection was overly restrictive, only starting the T5 shutdown guard timer when the association was in SHUTDOWN_PENDING state. This caused premature ABORTs when the receiver's rwnd was closed but the association was still in ESTABLISHED state. According to RFC 2960 Section 6.1, zero window probing is a normal protocol behavior. When rwnd is 0, the sender can always have one DATA chunk in flight to probe for a change in rwnd. Therefore, we should give the receiver a chance to recover by starting the T5 timer regardless of the association's current state. Fix this by removing the SHUTDOWN_PENDING state check, so that the T5 timer is started whenever zero_window_announced is true. Fixes: 8a0d19c5ed41 ("sctp: start t5 timer only when peer rwnd is 0 and local state is SHUTDOWN_PENDING") Assisted-by: LLM # review Signed-off-by: Qing Luo --- net/sctp/sm_statefuns.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c index 708fa07d5fff..b01db33bbc36 100644 --- a/net/sctp/sm_statefuns.c +++ b/net/sctp/sm_statefuns.c @@ -5842,8 +5842,7 @@ enum sctp_disposition sctp_sf_do_6_3_3_rtx(struct net *net, SCTP_INC_STATS(net, SCTP_MIB_T3_RTX_EXPIREDS); if (asoc->overall_error_count >= asoc->max_retrans) { - if (asoc->peer.zero_window_announced && - asoc->state == SCTP_STATE_SHUTDOWN_PENDING) { + if (asoc->peer.zero_window_announced) { /* * We are here likely because the receiver had its rwnd * closed for a while and we have not been able to -- 2.25.1