net/samba36 winbindd core dump on group lookup

Jeremy Chadwick freebsd at
Fri Dec 16 20:11:36 UTC 2011

On Fri, Dec 16, 2011 at 01:51:09PM -0600, Shaun Meyer wrote:
> freebsd-stable@,
> I'm building Samba using net/samba36 with the following config:
>      LDAP=on "With LDAP support"
>      ADS=on "With Active Directory support"
>      CUPS=off "With CUPS printing support"
>      WINBIND=on "With WinBIND support"
>      SWAT=off "With SWAT WebGUI"
>      ACL_SUPPORT=on "With ACL support"
>      AIO_SUPPORT=off "With Asyncronous IO support"
>      FAM_SUPPORT=off "With File Alteration Monitor"
>      SYSLOG=off "With Syslog support"
>      QUOTAS=on "With Disk quota support"
>      UTMP=off "With UTMP accounting support"
>      PAM_SMBPASS=off "With PAM authentication vs passdb backends"
>      DNSUPDATE=off "With dynamic DNS update(require ADS)"
>      AVAHI=off "With Bonjour service discovery support"
>      EXP_MODULES=on "With experimental modules"
>      POPT=on "With system-wide POPT library"
>      IPV6=on "With IPv6 support"
>      MAX_DEBUG=off "With maximum debugging"
>      SMBTORTURE=off "With smbtorture"
> I am able to join winbind to our 2003 domain, no problem. I'm using
> idmap_rid(8) backend and am using nss_winbind to enumerate uid/gid's.
> This set up runs fine for a few minutes (10?) until winbind begins
> dumping core when I do a group look up something like `getent group`
> or `id`.
> Before the core dumping begins: `wbinfo -g` returns all groups,
> `getent passwd` returns all users, `getent group` returns all groups,
> and `id [user]` returns all information as it should.
> After the core dumping begins: `wbinfo -g` returns all groups, `getent
> passwd` returns all users, `getent group` or `id [user]` causes a core
> dump in winbindd. The daemon continues running however.
> After the core dumping routine starts, I have to do some gyrations of
> `rm -rf /var/db/samba /usr/local/etc/samba`, restarting services, and
> joining/leaving the domain to get another ~10 minutes of functioning
> winbind.
> With MAX_DEBUG=on, I tried to use gdb on the winbindd.core file which
> shows lines like "#1627 0x0000000000000000 in ?? ()" and similar. I'm
> guessing this is to do with other system libs that are not compiled
> with -g, but I'm over my head here on FreeBSD system specifics.
> So I have two questions:
> 1) Will a buildworld with debugging symbols get me more meaningful
> output from gdb `backtrace full` and is this the best way?
> 2) Has anyone else experienced similar issues with net/samba36? I can
> reproduce this bug on both 9.0-RC2 and 8.2-RELEASE-p3.
> Your advice is appreciated,

Regarding MAX_DEBUG and trying to get a binary that's built with
debugging support -- you are correct.  Samba also has dependencies, as
you're familiar with, and all of those would need to be built with
debugging support as well.  Usually when there's a core with a calling
stack that's very long and all zeros, somewhere down at the bottom there
is something remotely coherent.  Keep in mind, however, that a software
crash can sometimes completely smash the contents of the calling stack,
which makes after-the-fact debugging very difficult.

I would strongly advise opening up a ticket with the Samba folks, as
well as posting this to freebsd-ports instead of freebsd-stable.  The
processes which are coring are purely Samba-specific.  Remember, ports
are third-party software, so starting there (with the Samba folks)
would be good.

| Jeremy Chadwick                                jdc at |
| Parodius Networking              |
| UNIX Systems Administrator                   Mountain View, CA, US |
| Making life hard for others since 1977.               PGP 4BD6C0CB |

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