Date: Mon, 15 Jan 2024 08:18:21 GMT From: Richard Scheffenegger <rscheff@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 04719681ba76 - stable/13 - tcp: prevent spurious empty segments and fix uncommon panic Message-ID: <202401150818.40F8ILU4084869@gitrepo.freebsd.org>
next in thread | raw e-mail | index | archive | help
The branch stable/13 has been updated by rscheff: URL: https://cgit.FreeBSD.org/src/commit/?id=04719681ba76a0756492b42313ea744503b78358 commit 04719681ba76a0756492b42313ea744503b78358 Author: Richard Scheffenegger <rscheff@FreeBSD.org> AuthorDate: 2024-01-08 08:25:39 +0000 Commit: Richard Scheffenegger <rscheff@FreeBSD.org> CommitDate: 2024-01-15 05:22:17 +0000 tcp: prevent spurious empty segments and fix uncommon panic Only try sending more data on pure ACKs when there is more data available in the send buffer. In the case of a retransmitted SYN not being sent due to an internal error, the snd_una/snd_nxt accounting could be off, leading to a panic. Pulling snd_nxt up to snd_una prevents this from happening. Reported by: fengdreamer@126.com Reviewed by: cc, tuexen, #transport MFC after: 1 week Sponsored by: NetApp, Inc. Differential Revision: https://reviews.freebsd.org/D43343 (cherry picked from commit f4574e2dc5a4719379496338257526aba484751b) --- sys/netinet/tcp_input.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c index 262e95d08071..af6afbd271bb 100644 --- a/sys/netinet/tcp_input.c +++ b/sys/netinet/tcp_input.c @@ -1943,7 +1943,13 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so, tcp_timer_activate(tp, TT_REXMT, tp->t_rxtcur); sowwakeup(so); - if (sbavail(&so->so_snd)) + /* + * Only call tcp_output when there + * is new data available to be sent + * or we need to send an ACK. + */ + if (SEQ_GT(tp->snd_una + sbavail(&so->so_snd), + tp->snd_max) || tp->t_flags & TF_ACKNOW) (void) tp->t_fb->tfb_tcp_output(tp); goto check_delack; } @@ -2112,6 +2118,8 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so, tp->rcv_adv += min(tp->rcv_wnd, TCP_MAXWIN << tp->rcv_scale); tp->snd_una++; /* SYN is acked */ + if (SEQ_LT(tp->snd_nxt, tp->snd_una)) + tp->snd_nxt = tp->snd_una; /* * If not all the data that was sent in the TFO SYN * has been acked, resend the remainder right away.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?202401150818.40F8ILU4084869>