From 8a92cb475ca90d84db769e4d4383e631ace0d6e5 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Sun, 26 Apr 2026 10:46:41 -0400 Subject: [PATCH] sctp: discard stale INIT after handshake completion MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit After an association reaches ESTABLISHED, the peer’s init_tag is already known from the handshake. Any subsequent INIT with the same init_tag is not a valid restart, but a delayed or duplicate INIT. Drop such INIT chunks in sctp_sf_do_unexpected_init() instead of processing them as new association attempts. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Link: https://patch.msgid.link/5788c76c1ee122a3ed00189e88dcf9df1fba226c.1777214801.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski --- net/sctp/sm_statefuns.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c index 7b823d759141..8e89a870780c 100644 --- a/net/sctp/sm_statefuns.c +++ b/net/sctp/sm_statefuns.c @@ -1556,6 +1556,12 @@ static enum sctp_disposition sctp_sf_do_unexpected_init( /* Tag the variable length parameters. */ chunk->param_hdr.v = skb_pull(chunk->skb, sizeof(struct sctp_inithdr)); + if (asoc->state >= SCTP_STATE_ESTABLISHED) { + /* Discard INIT matching peer vtag after handshake completion (stale INIT). */ + if (ntohl(chunk->subh.init_hdr->init_tag) == asoc->peer.i.init_tag) + return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); + } + /* Verify the INIT chunk before processing it. */ err_chunk = NULL; if (!sctp_verify_init(net, ep, asoc, chunk->chunk_hdr->type,