From: dtucker@openbsd.org <dtucker@openbsd.org>
Date: Fri, 11 Aug 2017 03:58:36 +0000 (+0000)
Subject: upstream commit
X-Git-Tag: V_7_6_P1~58
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b60ff20051ef96dfb207b6bfa45c0ad6c34a542a;p=thirdparty%2Fopenssh-portable.git

upstream commit

Keep track of the last time we actually heard from the
client and use this to also schedule a client_alive_check().  Prevents
activity on a forwarded port from indefinitely preventing the select timeout
so that client_alive_check() will eventually (although not optimally) be
called.

Analysis by willchan at google com via bz#2756, feedback & ok djm@

Upstream-ID: c08721e0bbda55c6d18e2760f3fe1b17fb71169e
---

diff --git a/serverloop.c b/serverloop.c
index b5eb3440a..4b8d5ba68 100644
--- a/serverloop.c
+++ b/serverloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: serverloop.c,v 1.193 2017/05/31 07:00:13 markus Exp $ */
+/* $OpenBSD: serverloop.c,v 1.194 2017/08/11 03:58:36 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -204,6 +204,7 @@ wait_until_can_do_something(int connection_in, int connection_out,
 	int ret;
 	time_t minwait_secs = 0;
 	int client_alive_scheduled = 0;
+	static time_t last_client_time;
 
 	/* Allocate and update select() masks for channel descriptors. */
 	channel_prepare_select(readsetp, writesetp, maxfdp, nallocp,
@@ -268,8 +269,19 @@ wait_until_can_do_something(int connection_in, int connection_out,
 		memset(*writesetp, 0, *nallocp);
 		if (errno != EINTR)
 			error("select: %.100s", strerror(errno));
-	} else if (ret == 0 && client_alive_scheduled)
-		client_alive_check();
+	} else if (client_alive_scheduled) {
+		time_t now = monotime();
+
+		if (ret == 0) { /* timeout */
+			client_alive_check();
+		} else if (FD_ISSET(connection_in, *readsetp)) {
+			last_client_time = now;
+		} else if (last_client_time != 0 && last_client_time +
+		    options.client_alive_interval < now) {
+			client_alive_check();
+			last_client_time = now;
+		}
+	}
 
 	notify_done(*readsetp);
 }