Commit c9158ceaf277 for kernel

commit c9158ceaf27780ef64534ad72f44ffde3f8ccc49
Author: Xin Long <lucien.xin@gmail.com>
Date:   Wed Aug 5 11:18:40 2026 -0400

    sctp: clear control chunk transport if it is being removed

    sctp_make_heartbeat_ack() caches the destination transport in
    chunk->transport without taking a reference. When src_out_of_asoc_ok is
    enabled, the HEARTBEAT ACK may remain queued on control_chunk_list instead
    of being transmitted immediately.

    If the peer transport is removed while the chunk is still queued,
    sctp_assoc_rm_peer() drops the transport and schedules it for RCU freeing,
    but only clears cached transport pointers in out_chunk_list.  The queued
    control chunk therefore retains a dangling transport pointer.

    Once an ASCONF_ACK clears the suppression and the queued control chunk is
    transmitted, SCTP dereferences the stale transport pointer, leading to a
    use-after-free.

    Fix this by also clearing chunk->transport for queued control chunks in
    control_chunk_list when removing the transport.

    Fixes: 8a07eb0a50ae ("sctp: Add ASCONF operation on the single-homed host")
    Reported-by: Daniele Linguaglossa <danielelinguaglossa@gmail.com>
    Signed-off-by: Xin Long <lucien.xin@gmail.com>
    Link: https://patch.msgid.link/7e1168cb722132152a29d47e5eafaeac4a3bf6f3.1785943120.git.lucien.xin@gmail.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/sctp/associola.c b/net/sctp/associola.c
index b6ac0966420a..5b0ae616e1ff 100644
--- a/net/sctp/associola.c
+++ b/net/sctp/associola.c
@@ -573,6 +573,10 @@ void sctp_assoc_rm_peer(struct sctp_association *asoc,
 		if (ch->transport == peer)
 			ch->transport = NULL;

+	list_for_each_entry(ch, &asoc->outqueue.control_chunk_list, list)
+		if (ch->transport == peer)
+			ch->transport = NULL;
+
 	asoc->peer.transport_count--;

 	sctp_ulpevent_notify_peer_addr_change(peer, SCTP_ADDR_REMOVED, 0);