inetd fd leak?

[Denys Vlasenko]

On Friday 04 September 2009 00:15, Doug Graham wrote:
> Cathey, Jim wrote:
> >> Let's try to simplify it. Try some (or all) of these:
> >>     
> >
> > Wilco.
> >
> >   
> >> * Run inetd with the same config on your own x?86 desktop.
> >>     
> >
> > That would be hard.  Not impossible, but hard.  (Not using
> > busybox at all there, is my development system and don't
> > want to screw it up.)  Might do that a bit later.
> >
> >   
> I can reproduce this in UML.  My image is Fedora Core 5 with glibc-2.4-11
> installed, and I built busybox 1.3.2 against glibc (not uClibc).  The 
> leak appears
> to be related to syslog.  For example, descriptor 6 was leaked, and 
> strace shows
> only these operations on that descriptor:
> 
> socket(PF_FILE, SOCK_DGRAM, 0)          = 6
> fcntl64(6, F_SETFD, FD_CLOEXEC)         = 0
> connect(6, {sa_family=AF_FILE, path="/dev/log"}, 110) = 0
> send(6, "<27>Sep  3 17:49:45 inetd[1938]:"..., 75, MSG_NOSIGNAL) = 75
> 
> After another run of bury.sh, the same thing happens on descriptor 7 
> (without 6
> being closed first).  The message being logged is this one:
> 
> Sep  3 17:49:45 uml0 inetd[1938]: telnet/tcp: too many connections, pausing
> 
> This is so totally weird that I figured it had to have something to do with
> vfork (just because vfork is so totally weird itself).  Replacing the 
> vfork in
> inetd.c with a fork instead does fix my leak.


Hmmm. Try inetd with option -e. If it stops leaking, we found it.

--
vda