[Bug 1584485] Re: Upgrading samba to latest security fixes together with winbind in nsswitch.conf can harm entire OS

Wed May 25 02:27:44 UTC 2016

** Patch added: "yakkety_samba_4.3.8+dfsg-0ubuntu2.debdiff"
   https://bugs.launchpad.net/ubuntu/+source/samba/+bug/1584485/+attachment/4669818/+files/yakkety_samba_4.3.8+dfsg-0ubuntu2.debdiff

** Description changed:

+ [Impact]
+ 
+ * Upgrading samba when using winbind as NSS can lead to loosing OS.
+ * Probable not noticed if "compat" is BEFORE "winbind" in nsswitch.conf.
+ * Huge impact due to big version different between winbind and libraries.
+ 
+ [Test Case]
+ 
+ * Comment #1 (to upgrade samba)
+ 
+ [Regression Potential]
+ 
+ * "preinst" and "postrm" maintainer scripts are acting only in "upgrade"
+ * uninstalling packages and reinstalling would bypass this change
+ 
+ [Other Info]
+ 
+ * Original Bug Description:
+ 
  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:

  https://bugs.launchpad.net/ubuntu/+source/samba/+bug/1584485/comments/1

  Leading into an unusable system in the following state:

  https://bugs.launchpad.net/ubuntu/+source/samba/+bug/1584485/comments/2

  ## state

  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.

** Tags added: sts

** Description changed:

  [Impact]

- * Upgrading samba when using winbind as NSS can lead to loosing OS.
- * Probable not noticed if "compat" is BEFORE "winbind" in nsswitch.conf.
+ * Upgrading samba when using winbind as NSS service can break OS.
+ * Probably not triggered if "compat" is BEFORE "winbind" in nsswitch.conf.
  * Huge impact due to big version different between winbind and libraries.

  [Test Case]

  * Comment #1 (to upgrade samba)

  [Regression Potential]

  * "preinst" and "postrm" maintainer scripts are acting only in "upgrade"
  * uninstalling packages and reinstalling would bypass this change

  [Other Info]

  * Original Bug Description:

  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:

  https://bugs.launchpad.net/ubuntu/+source/samba/+bug/1584485/comments/1

  Leading into an unusable system in the following state:

  https://bugs.launchpad.net/ubuntu/+source/samba/+bug/1584485/comments/2

  ## state

  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.

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https://bugs.launchpad.net/bugs/1584485

Title:
  Upgrading samba to latest security fixes together with winbind in
  nsswitch.conf can harm entire OS

Status in samba package in Ubuntu:
  Confirmed

Bug description:
  [Impact]

  * Upgrading samba when using winbind as NSS service can break OS.
  * Probably not triggered if "compat" is BEFORE "winbind" in nsswitch.conf.
  * Huge impact due to big version different between winbind and libraries.

  [Test Case]

  * Comment #1 (to upgrade samba)

  [Regression Potential]

  * "preinst" and "postrm" maintainer scripts are acting only in "upgrade"
  * uninstalling packages and reinstalling would bypass this change

  [Other Info]

  * Original Bug Description:

  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:

  https://bugs.launchpad.net/ubuntu/+source/samba/+bug/1584485/comments/1

  Leading into an unusable system in the following state:

  https://bugs.launchpad.net/ubuntu/+source/samba/+bug/1584485/comments/2

  ## state

  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.

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