Comment 0 for bug 1584485

It was brought to my attention that, because of latest security fixes for samba:

https://bugs.launchpad.net/ubuntu/+source/samba/+bug/1577739

samba (2:4.3.9+dfsg-0ubuntu0.14.04.1) trusty-security; urgency=medium
samba (2:4.3.8+dfsg-0ubuntu0.14.04.2) trusty-security; urgency=medium
samba (2:4.1.6+dfsg-1ubuntu2.14.04.13) trusty-security; urgency=medium

when library symbols changed, a samba upgrade MAY jeopardize an entire Ubuntu OS installation IF /etc/nsswitch.conf uses winbind as a service (specially if used before compat mechanism).

----

How to reproduce easily:

$ cat /etc/nsswitch.conf
passwd: winbind compat
shadow: compat
group: winbind compat

(winbind is usually used after compat, in this case it was used before)

to have samba version "4.1.6+dfsg-1ubuntu2.14.04.13" installed and do a:

$ sudo apt-get update

and FINALLY:

"""
$ sudo apt-get --only-upgrade install samba
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libhdb9-heimdal libkdc2-heimdal libntdb1 python-ntdb
Use 'apt-get autoremove' to remove them.
The following extra packages will be installed:
  libldb1 libnss-winbind libpam-winbind libtdb1 libtevent0 libwbclient0
  python-ldb python-samba python-tdb samba-common samba-common-bin
  samba-dsdb-modules samba-libs samba-vfs-modules winbind
Suggested packages:
  bind9 bind9utils ldb-tools smbldap-tools heimdal-clients
The following packages will be upgraded:
  libldb1 libnss-winbind libpam-winbind libtdb1 libtevent0 libwbclient0
  python-ldb python-samba python-tdb samba samba-common samba-common-bin
  samba-dsdb-modules samba-libs samba-vfs-modules winbind
16 upgraded, 0 newly installed, 0 to remove and 219 not upgraded.
Need to get 8,877 kB of archives.
After this operation, 5,632 kB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main python-ldb amd64 1:1.1.24-0ubuntu0.14.04.1 [29.2 kB]
Get:2 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main python-tdb amd64 1.3.8-0ubuntu0.14.04.1 [10.8 kB]
Get:3 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main libtdb1 amd64 1.3.8-0ubuntu0.14.04.1 [38.3 kB]
Get:4 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main libtevent0 amd64 0.9.28-0ubuntu0.14.04.1 [26.2 kB]
Get:5 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main samba-dsdb-modules amd64 2:4.3.9+dfsg-0ubuntu0.14.04.1 [219 kB]
Get:6 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/universe libnss-winbind amd64 2:4.3.9+dfsg-0ubuntu0.14.04.1 [12.6 kB]
Get:7 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/universe libpam-winbind amd64 2:4.3.9+dfsg-0ubuntu0.14.04.1 [28.2 kB]
Get:8 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main winbind amd64 2:4.3.9+dfsg-0ubuntu0.14.04.1 [411 kB]
Get:9 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main libwbclient0 amd64 2:4.3.9+dfsg-0ubuntu0.14.04.1 [30.8 kB]
Get:10 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main samba amd64 2:4.3.9+dfsg-0ubuntu0.14.04.1 [903 kB]
Get:11 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main samba-common-bin amd64 2:4.3.9+dfsg-0ubuntu0.14.04.1 [508 kB]
Get:12 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main samba-common all 2:4.3.9+dfsg-0ubuntu0.14.04.1 [82.9 kB]
Get:13 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main python-samba amd64 2:4.3.9+dfsg-0ubuntu0.14.04.1 [1,068 kB]
Get:14 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main samba-vfs-modules amd64 2:4.3.9+dfsg-0ubuntu0.14.04.1 [259 kB]
Get:15 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main samba-libs amd64 2:4.3.9+dfsg-0ubuntu0.14.04.1 [5,144 kB]
Get:16 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main libldb1 amd64 1:1.1.24-0ubuntu0.14.04.1 [107 kB]
Fetched 8,877 kB in 14s (594 kB/s)
Preconfiguring packages ...
(Reading database ... 115393 files and directories currently installed.)
Preparing to unpack .../python-ldb_1%3a1.1.24-0ubuntu0.14.04.1_amd64.deb ...
Unpacking python-ldb (1:1.1.24-0ubuntu0.14.04.1) over (1:1.1.16-1ubuntu0.1) ...
Preparing to unpack .../python-tdb_1.3.8-0ubuntu0.14.04.1_amd64.deb ...
Unpacking python-tdb (1.3.8-0ubuntu0.14.04.1) over (1.2.12-1) ...
Preparing to unpack .../libtdb1_1.3.8-0ubuntu0.14.04.1_amd64.deb ...
Unpacking libtdb1:amd64 (1.3.8-0ubuntu0.14.04.1) over (1.2.12-1) ...
Preparing to unpack .../libtevent0_0.9.28-0ubuntu0.14.04.1_amd64.deb ...
Unpacking libtevent0:amd64 (0.9.28-0ubuntu0.14.04.1) over (0.9.19-1) ...
Preparing to unpack .../samba-dsdb-modules_2%3a4.3.9+dfsg-0ubuntu0.14.04.1_amd64.deb ...
Unpacking samba-dsdb-modules (2:4.3.9+dfsg-0ubuntu0.14.04.1) over (2:4.1.6+dfsg-1ubuntu2.14.04.13) ...
Preparing to unpack .../libnss-winbind_2%3a4.3.9+dfsg-0ubuntu0.14.04.1_amd64.deb ...
Unpacking libnss-winbind:amd64 (2:4.3.9+dfsg-0ubuntu0.14.04.1) over (2:4.1.6+dfsg-1ubuntu2.14.04.13) ...
dpkg-deb: error: subprocess tar was killed by signal (Segmentation fault), core dumped
dpkg: error processing archive /var/cache/apt/archives/libpam-winbind_2%3a4.3.9+dfsg-0ubuntu0.14.04.1_amd64.deb (--unpack):
 subprocess dpkg-deb --control returned error exit status 2
dpkg-deb: error: subprocess tar was killed by signal (Segmentation fault), core dumped
dpkg: error processing archive /var/cache/apt/archives/winbind_2%3a4.3.9+dfsg-0ubuntu0.14.04.1_amd64.deb (--unpack):
 subprocess dpkg-deb --control returned error exit status 2
dpkg-deb: error: subprocess tar was killed by signal (Segmentation fault), core dumped
dpkg: error processing archive /var/cache/apt/archives/libwbclient0_2%3a4.3.9+dfsg-0ubuntu0.14.04.1_amd64.deb (--unpack):
 subprocess dpkg-deb --control returned error exit status 2
dpkg-deb: error: subprocess tar was killed by signal (Segmentation fault), core dumped
"""

Leading into an unusable system.

Workaround:

DO REMOVE winbind from /etc/nsswitch.conf (and possibly from pam.d with "pam-auth-update") before ANY attempt of upgrading samba to latest version.