samba PANIC: failed to set uid

[Jan Schneider]

Binary package hint: samba

Samba crashes with the following backtrace:

[2009/02/27 10:30:21, 0] lib/util_sec.c:assert_uid(101)
  Failed to set uid privileges to (11789,11789) now set to (0,0)
[2009/02/27 10:30:21, 0] lib/util.c:smb_panic(1633)
  PANIC (pid 27857): failed to set uid

[2009/02/27 10:30:21, 0] lib/util.c:log_stack_trace(1737)
  BACKTRACE: 15 stack frames:
   #0 /usr/sbin/smbd(log_stack_trace+0x1c) [0x613b4c]
   #1 /usr/sbin/smbd(smb_panic+0x43) [0x613c33]
   #2 /usr/sbin/smbd [0x618cf1]
   #3 /usr/sbin/smbd [0x61b8ab]
   #4 /usr/sbin/smbd [0x61bbbb]
   #5 /usr/sbin/smbd(messaging_send+0x20) [0x61bfd0]
   #6 /usr/sbin/smbd(notify_trigger+0x2a1) [0x64a0e1]
   #7 /usr/sbin/smbd(notify_fname+0x50) [0x648440]
   #8 /usr/sbin/smbd(rename_internals+0xdca) [0x48f3ea]
   #9 /usr/sbin/smbd(reply_mv+0x239) [0x4966c9]
   #10 /usr/sbin/smbd [0x4c87ce]
   #11 /usr/sbin/smbd(smbd_process+0x7e2) [0x4c9bc2]
   #12 /usr/sbin/smbd(main+0x8cd) [0x6c5fad]
   #13 /lib/libc.so.6(__libc_start_main+0xf4) [0x7fae3332f1c4]
   #14 /usr/sbin/smbd [0x45a899]
[2009/02/27 10:30:21, 0] lib/fault.c:dump_core(181)
  dumping core in /var/log/samba/cores/smbd

Seems not to be client-specific.
Occures only with more than about 100 clients connected.

Ubuntu version: 8.04.2 (amd64)
Samba version: 3.0.28a-1ubuntu4.7

FIX:
Build the sernet samba packages from source (3.0.34):
http://ftp.sernet.de/pub/samba/old/src/debian/3.0.34

[Paul Dufresne (paulduf)]

Thank you for this bug report.
Many other similar bugs have been reported, some on Ubuntu, sometimes on Fedora, or even in FreeBSD.
In Ubuntu I speak of bug #216358, bug #314657 and bug #229654.

Could you check if user ID 11789 really exist by doing:
sudo cat /etc/passwd | grep 11789
sudo cat /etc/group | grep 11789

and if so, try to become this user with "su <user>" and issue
ulimit -u
and give the result here.

[Jan Schneider (j-schneider-uib)]

Yes, i have seen a lot of similar bug reports too, but all of them were unresolved.

When the problem appeared we checked a lot of configuration issues.
The problem seems NOT to be user or client specific.
The users where the PANIC appeared:
 - had a unix account
 - a samba account with the same uid
 - no special ulimits set
 - no group membership which seems to be responsible for the problem
 - su <user> did work, opening files as this user did work, no messages like: to many open files...

# getent passwd 11789
diehl:x:11789:11700::/home/diehl:/bin/bash

# pdbedit -L -u diehl
diehl:11789:

# su - diehl -c 'ulimit -u'
30720

# getent group 11700
<groupname>:x:11700:

# net groupmap list | grep <groupname>
<groupname> (<SID>) -> <groupname>

Samba worked without any problems if there were less than about 100 clients/users connected.

Volker Lendecke from SerNet proposed to set "change notify = no" as a workaround, which we did not really test.

If you need more information, please let me know, but since this server acts as a domain controller in an productive environment I cannot reproduce the bug.

[Paul Dufresne (paulduf)]

I think you did the right thing by installing Samba 3.0.34.
Indeed the changelog suggest that it was fixed there:
http://www.samba.org/samba/history/samba-3.0.34.html
o Andrew Tridgell
    * Avoid a race condition in glibc between AIO and setresuid().
    * Become root for AIO operations.

2009/3/16, Jan Schneider <email address hidden>:
> Yes, i have seen a lot of similar bug reports too, but all of them were
> unresolved.
>
> When the problem appeared we checked a lot of configuration issues.
> The problem seems NOT to be user or client specific.
> The users where the PANIC appeared:
> - had a unix account
> - a samba account with the same uid
> - no special ulimits set
> - no group membership which seems to be responsible for the problem
> - su <user> did work, opening files as this user did work, no messages
> like: to many open files...
>
> # getent passwd 11789
> diehl:x:11789:11700::/home/diehl:/bin/bash
>
> # pdbedit -L -u diehl
> diehl:11789:
>
> # su - diehl -c 'ulimit -u'
> 30720
>
> # getent group 11700
> <groupname>:x:11700:
>
> # net groupmap list | grep <groupname>
> <groupname> (<SID>) -> <groupname>
>
> Samba worked without any problems if there were less than about 100
> clients/users connected.
>
> Volker Lendecke from SerNet proposed to set "change notify = no" as a
> workaround, which we did not really test.
>
> If you need more information, please let me know, but since this server
> acts as a domain controller in an productive environment I cannot
> reproduce the bug.
>
> --
> samba PANIC: failed to set uid
> https://bugs.launchpad.net/bugs/341816
> You received this bug notification because you are a direct subscriber
> of the bug.
>

[Thierry Carrez (ttx)]

This might not be a duplicate of bug 216358.
Could the reporter try the packages in my PPA and see if they fix it for him (as well as 3.0.34 did).
(samba_3.0.28a-1ubuntu4.9~ppa1) at https://launchpad.net/~ttx/+archive/ppa
Thanks !

[Jan Schneider (j-schneider-uib)]

Sorry, as I said before, I can't try the package because it is a productive environment...

[Cory Coager (ccoager)]

Having the same issue here:
kernel 2.6.24-23-server x64
samba 3.0.28a-1ubuntu4.9

The setting "change notify = no" seems to work as a workaround.

[Chuck Short (zulcss)]

I am going to mark this as fixed released, but this is probably a good candidate for an SRU.

chuck