svn commit: r304100 - stable/11/sbin/route

[Andrey V. Elsukov]

Author: ae
Date: Sun Aug 14 20:19:47 2016
New Revision: 304100
URL: https://svnweb.freebsd.org/changeset/base/304100

Log:
  MFC r303374:
    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.

Modified:
  stable/11/sbin/route/route.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sbin/route/route.c
==============================================================================
--- stable/11/sbin/route/route.c	Sun Aug 14 19:54:40 2016	(r304099)
+++ stable/11/sbin/route/route.c	Sun Aug 14 20:19:47 2016	(r304100)
@@ -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 *
 
 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