Bug on ssh-agent (following my first report)

[Damien Miller]

On Thu, 5 Jan 2006, Frédéric Olivié wrote:

> Damien Miller a écrit :
> > Please don't send HTML mail.
> >   
> Sorry. Hope this is better (I asked Thunderbird to send text-only on this
> list).
> > 
> > Please try this diff:
> >   
> It can't work. The "continue" statement causes "dupfd++" never to be evaluated
> thus resulting in an infinite loop.

This is better:

Index: misc.c
===================================================================
RCS file: /cvs/src/usr.bin/ssh/misc.c,v
retrieving revision 1.40
diff -u -p -r1.40 misc.c
--- misc.c	2 Jan 2006 07:53:44 -0000	1.40
+++ misc.c	5 Jan 2006 04:23:44 -0000
@@ -601,18 +601,20 @@ tun_open(int tun, int mode)
 void
 sanitise_stdfd(void)
 {
-	int nullfd;
+	int nullfd, dupfd;
 
-	if ((nullfd = open(_PATH_DEVNULL, O_RDWR)) == -1) {
+	if ((nullfd = dupfd = open(_PATH_DEVNULL, O_RDWR)) == -1) {
 		fprintf(stderr, "Couldn't open /dev/null: %s", strerror(errno));
 		exit(1);
 	}
-	while (nullfd < 2) {
-		if (dup2(nullfd, nullfd + 1) == -1) {
+	while (++dupfd <= 2) {
+		/* Only clobber closed fds */
+		if (fcntl(dupfd, F_GETFL, 0) >= 0)
+			continue;
+		if (dup2(nullfd, dupfd) == -1) {
 			fprintf(stderr, "dup2: %s", strerror(errno));
 			exit(1);
 		}
-		nullfd++;
 	}
 	if (nullfd > 2)
 		close(nullfd);