From 47a8e86509b258d16c4a36e2e475cb946bbc447c Mon Sep 17 00:00:00 2001 From: Xin LI Date: Tue, 21 Jul 2015 23:42:15 +0000 Subject: Fix resource exhaustion due to sessions stuck in LAST_ACK state. Submitted by: Jonathan Looney (Juniper SIRT) Reviewed by: lstewart Security: CVE-2015-5358 Security: SA-15:13.tcp --- sys/netinet/tcp_output.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'sys/netinet/tcp_output.c') diff --git a/sys/netinet/tcp_output.c b/sys/netinet/tcp_output.c index 111f22e2edda..9413721624cb 100644 --- a/sys/netinet/tcp_output.c +++ b/sys/netinet/tcp_output.c @@ -400,7 +400,7 @@ after_sack_rexmit: flags &= ~TH_FIN; } - if (len < 0) { + if (len <= 0) { /* * If FIN has been sent but not acked, * but we haven't been called to retransmit, @@ -410,9 +410,16 @@ after_sack_rexmit: * to (closed) window, and set the persist timer * if it isn't already going. If the window didn't * close completely, just wait for an ACK. + * + * We also do a general check here to ensure that + * we will set the persist timer when we have data + * to send, but a 0-byte window. This makes sure + * the persist timer is set even if the packet + * hits one of the "goto send" lines below. */ len = 0; - if (sendwin == 0) { + if ((sendwin == 0) && (TCPS_HAVEESTABLISHED(tp->t_state)) && + (off < (int) sbavail(&so->so_snd))) { tcp_timer_activate(tp, TT_REXMT, 0); tp->t_rxtshift = 0; tp->snd_nxt = tp->snd_una; -- cgit v1.2.3