From 0cd2dc6dce8ca47212cd306ccd52eb315ef3cf85 Mon Sep 17 00:00:00 2001 From: Wyatt Feng Date: Fri, 5 Jun 2026 13:53:42 +0800 Subject: [PATCH] sctp: stream: fully roll back denied add-stream state commit a5f8a90ac9f77c678a9781c0a464b635e0d63e49 upstream. When ADD_OUT_STREAMS is denied, SCTP only shrinks the queued chunks and then lowers outcnt. That leaves removed stream metadata behind, so a later re-add can reuse a stale ext and hit a null-pointer dereference in the scheduler get path. Fix the rollback by tearing down the removed stream state the same way other stream resizes do. Unschedule the current scheduler state, drop the removed stream ext state with sctp_stream_outq_migrate(), and then reschedule the remaining streams. This keeps scheduler-private RR/FC/PRIO lists consistent while fully rolling back denied outgoing stream additions. Fixes: 637784ade221 ("sctp: introduce priority based stream scheduler") Cc: stable@kernel.org Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Zhengchuan Liang Reported-by: Xin Liu Signed-off-by: Wyatt Feng Signed-off-by: Ren Wei Acked-by: Xin Long Link: https://patch.msgid.link/d78954ecd94954653ee299400e98d74a03a6f7d3.1780603399.git.bronzed_45_vested@icloud.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/sctp/stream.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/sctp/stream.c b/net/sctp/stream.c index 0527728aee98..d38e5431f359 100644 --- a/net/sctp/stream.c +++ b/net/sctp/stream.c @@ -1038,6 +1038,7 @@ struct sctp_chunk *sctp_process_strreset_resp( stsn, rtsn, GFP_ATOMIC); } else if (req->type == SCTP_PARAM_RESET_ADD_OUT_STREAMS) { struct sctp_strreset_addstrm *addstrm; + const struct sctp_sched_ops *sched; __u16 number; addstrm = (struct sctp_strreset_addstrm *)req; @@ -1048,7 +1049,10 @@ struct sctp_chunk *sctp_process_strreset_resp( for (i = number; i < stream->outcnt; i++) SCTP_SO(stream, i)->state = SCTP_STREAM_OPEN; } else { - sctp_stream_shrink_out(stream, number); + sched = sctp_sched_ops_from_stream(stream); + sched->unsched_all(stream); + sctp_stream_outq_migrate(stream, NULL, number); + sched->sched_all(stream); stream->outcnt = number; }