From 5a91e32b40af86c790c4348aa3a5926a5c5fbc6d Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Thu, 30 Apr 2020 15:01:54 +0200 Subject: [PATCH] mptcp: fix 'use_ack' option access. The mentioned RX option field is initialized only for DSS packet, we must access it only if 'dss' is set too, or the subflow will end-up in a bad status, leading to RFC violations. Fixes: d22f4988ffec ("mptcp: process MP_CAPABLE data option") Signed-off-by: Paolo Abeni Signed-off-by: David S. Miller --- net/mptcp/options.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/mptcp/options.c b/net/mptcp/options.c index ecf41d52d2fc..9486720c3256 100644 --- a/net/mptcp/options.c +++ b/net/mptcp/options.c @@ -695,7 +695,7 @@ static bool check_fully_established(struct mptcp_sock *msk, struct sock *sk, if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) return subflow->mp_capable; - if (mp_opt->use_ack) { + if (mp_opt->dss && mp_opt->use_ack) { /* subflows are fully established as soon as we get any * additional ack. */ -- 2.20.1