From d625f4ac989512ef9fabc63219fdf74a4a7b32cb Mon Sep 17 00:00:00 2001 From: Shreeya Patel Date: Wed, 9 Sep 2026 11:44:12 +0000 Subject: [PATCH 1/2] sctp: purge outqueue on stale COOKIE-ECHO handling jira VULN-189044 cve CVE-2026-52924 commit-author Xin Long commit e374b22e9b07b72a25909621464ff74096151bfb sctp_stream_update() is only invoked when the association is moved into COOKIE_WAIT during association setup/reconfiguration. In this path, the outbound stream scheduler state (stream->out_curr) is expected to be clean, since no user data should have been transmitted yet unless the state machine has already partially progressed. However, a corner case exists in sctp_sf_do_5_2_6_stale(): when a Stale Cookie ERROR is received, the association is rolled back from COOKIE_ECHOED to COOKIE_WAIT. In this scenario, user data may already have been queued and even bundled with the COOKIE-ECHO chunk. During the rollback, sctp_stream_update() frees the old stream table and installs a new one, but it does not invalidate stream->out_curr. As a result, out_curr may still point to a freed sctp_stream_out entry from the previous stream state. Later, SCTP scheduler dequeue paths (FCFS, RR, PRIO, etc.) rely on stream->out_curr->ext, which can lead to use-after-free once the old stream state has been released via sctp_stream_free(). This results in crashes such as (reported by Yuqi): BUG: KASAN: slab-use-after-free in sctp_sched_fcfs_dequeue+0x13a/0x140 Read of size 8 at addr ff1100004d4d3208 by task mini_poc/9312 CPU: 1 UID: 1001 PID: 9312 Comm: mini_poc Not tainted 7.1.0-rc1-00305-gbd3a4795d574 #5 PREEMPT(full) sctp_sched_fcfs_dequeue+0x13a/0x140 sctp_outq_flush+0x1603/0x33e0 sctp_do_sm+0x31c9/0x5d30 sctp_assoc_bh_rcv+0x392/0x6f0 sctp_inq_push+0x1db/0x270 sctp_rcv+0x138d/0x3c10 Fix this by fully purging the association outqueue when handling the Stale Cookie case. This ensures all pending transmit and retransmit state is dropped, and any scheduler cached pointers are invalidated, making it safe to rebuild stream state during COOKIE_WAIT restart. Updating only stream->out_curr would be insufficient, since queued and retransmittable data would still reference the old stream state and trigger later use-after-free in dequeue paths. Fixes: 5bbbbe32a431 ("sctp: introduce stream scheduler foundations") Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Zhengchuan Liang Reported-by: Xin Liu Reported-by: Yuqi Xu Reported-by: Ren Wei Signed-off-by: Xin Long Link: https://patch.msgid.link/94318159b9052907a6cbb7256aee8b5f8dfbfccb.1780510304.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski (cherry picked from commit e374b22e9b07b72a25909621464ff74096151bfb) Signed-off-by: Shreeya Patel --- net/sctp/sm_statefuns.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c index 240863817000a..3ebfe32771035 100644 --- a/net/sctp/sm_statefuns.c +++ b/net/sctp/sm_statefuns.c @@ -2596,11 +2596,7 @@ static enum sctp_disposition sctp_sf_do_5_2_6_stale( */ sctp_add_cmd_sf(commands, SCTP_CMD_DEL_NON_PRIMARY, SCTP_NULL()); - /* If we've sent any data bundled with COOKIE-ECHO we will need to - * resend - */ - sctp_add_cmd_sf(commands, SCTP_CMD_T1_RETRAN, - SCTP_TRANSPORT(asoc->peer.primary_path)); + sctp_add_cmd_sf(commands, SCTP_CMD_PURGE_OUTQUEUE, SCTP_NULL()); /* Cast away the const modifier, as we want to just * rerun it through as a sideffect. From f6c11eef7649fc48805104334cdb3d50c07dc0f2 Mon Sep 17 00:00:00 2001 From: Shreeya Patel Date: Wed, 9 Sep 2026 11:44:21 +0000 Subject: [PATCH 2/2] sctp: stream: fully roll back denied add-stream state jira VULN-189063 cve CVE-2026-52929 commit-author Wyatt Feng commit a5f8a90ac9f77c678a9781c0a464b635e0d63e49 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 (cherry picked from commit a5f8a90ac9f77c678a9781c0a464b635e0d63e49) Signed-off-by: Shreeya Patel --- 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 37ff85cc2bb29..82891699a9c00 100644 --- a/net/sctp/stream.c +++ b/net/sctp/stream.c @@ -1076,6 +1076,7 @@ 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; @@ -1086,7 +1087,10 @@ 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; }