From 6a5d9be9fe56f8cffa872e4af2ca8a817fd557a5 Mon Sep 17 00:00:00 2001
From: "Andrey V. Elsukov" <ae@FreeBSD.org>
Date: Wed, 27 Jul 2016 08:26:34 +0000
Subject: [PATCH] Due to dropped mbuf in netisr queue route(8) can fall into
 infinity loop of reading the rtsock's feed. When it used by some scripts,
 this leads to growing number of not finished route(8) instances and thus
 growing number of rtsock consumers. Add SIGALRM handler to prevent this.

Reviewed by:	melifaro
Obtained from:	Yandex LLC
MFC after:	2 weeks
Sponsored by:	Yandex LLC
---
 sbin/route/route.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/sbin/route/route.c b/sbin/route/route.c
index a357a4d03851..ee312a4d36cb 100644
--- a/sbin/route/route.c
+++ b/sbin/route/route.c
@@ -62,6 +62,7 @@ __FBSDID("$FreeBSD$");
 #include <err.h>
 #include <errno.h>
 #include <paths.h>
+#include <signal.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -144,6 +145,16 @@ static int	fiboptlist_range(const char *, struct fibl_head_t *);
 
 static void usage(const char *) __dead2;
 
+#define	READ_TIMEOUT	10
+static volatile sig_atomic_t stop_read;
+
+static void
+stopit(int sig __unused)
+{
+
+	stop_read = 1;
+}
+
 static void
 usage(const char *cp)
 {
@@ -776,6 +787,7 @@ set_metric(char *value, int key)
 static void
 newroute(int argc, char **argv)
 {
+	struct sigaction sa;
 	struct hostent *hp;
 	struct fibl *fl;
 	char *cmd;
@@ -791,6 +803,12 @@ newroute(int argc, char **argv)
 	hp = NULL;
 	TAILQ_INIT(&fibl_head);
 
+	sigemptyset(&sa.sa_mask);
+	sa.sa_flags = 0;
+	sa.sa_handler = stopit;
+	if (sigaction(SIGALRM, &sa, 0) == -1)
+		warn("sigaction SIGALRM");
+
 	cmd = argv[0];
 	if (*cmd != 'g' && *cmd != 's')
 		shutdown(s, SHUT_RD); /* Don't want to read back our messages */
@@ -1541,9 +1559,17 @@ rtmsg(int cmd, int flags, int fib)
 		return (-1);
 	}
 	if (cmd == RTM_GET) {
+		stop_read = 0;
+		alarm(READ_TIMEOUT);
 		do {
 			l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
-		} while (l > 0 && (rtm.rtm_seq != rtm_seq || rtm.rtm_pid != pid));
+		} while (l > 0 && stop_read == 0 &&
+		    (rtm.rtm_seq != rtm_seq || rtm.rtm_pid != pid));
+		if (stop_read != 0) {
+			warnx("read from routing socket timed out");
+			return (-1);
+		} else
+			alarm(0);
 		if (l < 0)
 			warn("read from routing socket");
 		else