[Bug 777855] Re: resolver failures without even sending queries, break Postfix

[Matthias Andree]

Am 06.08.2011 17:05, schrieb Clint Byrum:

> I think we can also close the task on Postfix, since this is a glibc
> issue, unless there is something we can do to postfix to fix this.

Postfix is one of the few software packages whose default configuration
(in newer Postfix versions) triggers this bug.  If you choose to fix
glibc through SRUs, then you can, of course, close the Postfix relation.

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https://bugs.launchpad.net/bugs/777855

Title:
  resolver failures without even sending queries, break Postfix

Status in The GNU C Library:
  Fix Released
Status in “eglibc” package in Ubuntu:
  Fix Released
Status in “postfix” package in Ubuntu:
  Confirmed
Status in “eglibc” source package in Lucid:
  Confirmed
Status in “postfix” source package in Lucid:
  New
Status in “eglibc” source package in Maverick:
  New
Status in “postfix” source package in Maverick:
  New
Status in “eglibc” source package in Natty:
  Confirmed
Status in “postfix” source package in Natty:
  Confirmed
Status in “glibc” package in openSUSE:
  In Progress

Bug description:
  The eglibc resolver is broken and doesn't attempt DNS queries for
  hostnames without dots if the RES_DEFNAMES option gets stripped from
  the _res.options (resolver options).

  This breaks security-sensitive applications (I'd first observed it
  with Postfix) trying to resolve, for instance, localhost, thus:

  res_init();
  _res.options &= ~RES_DEFNAMES;
  int result = res_search("localhost", C_IN, T_A, buf, sizeof buffer);

  returns failure with HOST_NOT_FOUND even if the name server has a
  localhost zone. FreeBSD and Solaris don't have this bug.

  I've reported this upstream as
  http://sourceware.org/bugzilla/show_bug.cgi?id=12734 where you'll find
  more details.

  ProblemType: Bug
  DistroRelease: Ubuntu 11.04
  Package: libc6 2.13-0ubuntu13
  ProcVersionSignature: Ubuntu 2.6.38-9.43-generic 2.6.38.4
  Uname: Linux 2.6.38-9-generic x86_64
  NonfreeKernelModules: fglrx
  Architecture: amd64
  Date: Thu May  5 15:55:40 2011
  ProcEnviron:
   LANGUAGE=de:en
   PATH=(custom, no user)
   LANG=de_DE.UTF-8
   SHELL=/bin/bash
  SourcePackage: eglibc
  UpgradeStatus: Upgraded to natty on 2011-05-02 (3 days ago)

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