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[Steve Langasek <steve.langasek@xxxxxxxxxxxxx>]

In source3/passdb/pdb_interface.c, pdb_get_methods_reload() assumes that
pdb->free_private_data will always be set and callable.  This is not the
case for the tdbsam backend, which has:

        /* no private data */

        (*pdb_method)->private_data      = NULL;
        (*pdb_method)->free_private_data = NULL;

(source3/passdb/pdb_tdb.c)

and pam_smbpass does call initialize_password_db(True, NULL), which
triggers this codepath.

The only thing that's not clear to me is why people haven't been
reporting this issue in droves before now.  Tamer, have you configured
pam_smbpass to be used for account authorization in addition to
authentication?  Can you attach /etc/pam.d/common-* and
/etc/pam.d/lightdm?

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https://bugs.launchpad.net/bugs/829221

Title:
  lightdm crashed with SIGSEGV in initialize_password_db()

Status in “lightdm” package in Ubuntu:
  Confirmed
Status in “samba” package in Ubuntu:
  Confirmed
Status in “lightdm” source package in Oneiric:
  Confirmed
Status in “samba” source package in Oneiric:
  Confirmed

Bug description:
  Happens on every login afer upgrading from 11.04

  ProblemType: Crash
  DistroRelease: Ubuntu 11.10
  Package: lightdm 0.9.3-0ubuntu5
  ProcVersionSignature: Ubuntu 3.0.0-8.11-generic 3.0.1
  Uname: Linux 3.0.0-8-generic x86_64
  NonfreeKernelModules: nvidia
  Architecture: amd64
  Date: Fri Aug 19 00:59:54 2011
  Disassembly: => 0x0:	Cannot access memory at address 0x0
  ExecutablePath: /usr/sbin/lightdm
  InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release amd64 (20101007)
  ProcCmdline: lightdm
  ProcCwd: /
  ProcEnviron: PATH=(custom, no user)
  SegvAnalysis:
   Segfault happened at: 0x0:	Cannot access memory at address 0x0
   PC (0x00000000) not located in a known VMA region (needed executable region)!
   Stack memory exhausted (SP below stack segment)
  SegvReason: executing NULL VMA
  Signal: 11
  SourcePackage: lightdm
  StacktraceTop:
   ?? ()
   ?? () from /lib/security/pam_smbpass.so
   initialize_password_db () from /lib/security/pam_smbpass.so
   pam_sm_authenticate () from /lib/security/pam_smbpass.so
   ?? () from /lib/x86_64-linux-gnu/libpam.so.0
  Title: lightdm crashed with SIGSEGV in initialize_password_db()
  UpgradeStatus: Upgraded to oneiric on 2011-08-18 (0 days ago)
  UserGroups:

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