Date: Sun, 28 Dec 2003 18:21:09 +0000 (UTC) From: "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net> To: David Malone <dwmalone@maths.tcd.ie> Cc: freebsd-current@freebsd.org Subject: Re: file descriptor leak in 5.2-RC Message-ID: <Pine.BSF.4.53.0312281815210.21415@e0-0.zab2.int.zabbadoz.net> In-Reply-To: <20031228180536.GA49762@walton.maths.tcd.ie> References: <20031227205000.GG86308@e-Gitt.NET> <1035.1072561906@critter.freebsd.dk> <20031228180536.GA49762@walton.maths.tcd.ie>
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On Sun, 28 Dec 2003, David Malone wrote:
> > I'd call it a surprise if someone after all had a fix within the next 10
> > hours or so.
>
> I'm fairly certain I've found the problem (and, indeed, it looks
> like I introduced it too while changing how falloc works). You loose
> a reference to /dev/null every time you exec a suid program with
> at least one of std{in,out,err} closed. I'm guessing that some part
> of postfix does this.
>
> I believe the patch below will fix the problem. I guess I'm too
> late for you to test it now?
I think it's the correct place...
I could not reproduce the problem on a machine with a kernel
from late september.
Ok, now that we have the patch I can also send a simple program to
test it out to the list ...
Be aware that local users can eat a lot of fds with that ... on
current and 5.2-prereleases
--- end ---
cat > exec-closed123-ping.c <<EOF
#include <unistd.h>
#ifndef MAX_CHILDS
#define MAX_CHILDS 16
#endif
static int _execsetuid()
{
execl("/sbin/ping", "-c", "1", "localhost", NULL);
return 1;
}
int main(int argc, char *argv[])
{
int i = 0;
pid_t pid;
(void) close(0);
(void) close(1);
(void) close(2);
while (i++ < MAX_CHILDS) {
pid = fork();
switch (pid) {
case 0:
_exit(_execsetuid());
}
}
return 0;
}
EOF
gcc -Wall exec-closed123-ping.c -o exec-closed123-ping
sysctl kern.openfiles
./exec-closed123-ping
sysctl kern.openfiles
--- end ---
there should be a difference of 16 in kern.openfiles.
--
Bjoern A. Zeeb bzeeb at Zabbadoz dot NeT
56 69 73 69 74 http://www.zabbadoz.net/
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