pam-0.79: Bug in pam_tally:tally_get_data?

[Andreas Haumer]

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Hi!

I'm currently hunting a bug after upgrading to pam-0.79 and I'm
wondering if anyone has found similar problems.

Symptom: programs using the pam_tally module (like login)
are crashing with SIGSEGV in the tally_get_data function.

Look at the following gdb session:

root at tolstoi:/work/shadow-4.0.7/src {633} $ gdb login
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GDB is free software, covered by the GNU General Public License, and you are
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This GDB was configured as "i686-pc-linux-gnu"...Using host libthread_db library "/lib/libthread_db.so.1".

(gdb) r andreas
Starting program: /work/shadow-4.0.7/src/login andreas
Password:

Program received signal SIGSEGV, Segmentation fault.
0x401da219 in tally_get_data () from /lib/security/pam_tally.so
(gdb) bt
#0  0x401da219 in tally_get_data () from /lib/security/pam_tally.so
#1  0x401dac1a in pam_sm_setcred () from /lib/security/pam_tally.so
#2  0x400479e5 in _pam_dispatch_aux () from /lib/libpam.so.0
#3  0x40047b60 in _pam_dispatch () from /lib/libpam.so.0
#4  0x40049992 in pam_setcred () from /lib/libpam.so.0
#5  0x0804a8d6 in main (argc=5, argv=0xbfffecc4) at login.c:796

This crash happens with the login program from the shadow-4.0.7
and shadow-4.0.9 packages (these are the only versions I have tested).
I'm using Linux with glibc-2.3.5 and kernel 2.4.31, if that matters.

If I replace the pam_tally module with the module from pam-0.78,
everything is fine. Also, when I remove the pam_tally module from
the pam stack, the segmentation fault disappears even with pam-0.79

It seems the major rewrite of the pam_tally module in pam-0.79
has introduced some problems...

HTH

- - andreas

PS: While hunting this bug, I found that the online documentation
of the pam_tally module as found on the PAM website at kernel.org
is outdated, as some options have changed name and/or semantics
during the rewrite im pam-0.79.

- --
Andreas Haumer                     | mailto:andreas at xss.co.at
*x Software + Systeme              | http://www.xss.co.at/
Karmarschgasse 51/2/20             | Tel: +43-1-6060114-0
A-1100 Vienna, Austria             | Fax: +43-1-6060114-71

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