Synopsis

Moderate: glibc security and bug fix update

Type/Severity

Security Advisory: Moderate

Topic

Updated glibc packages that fix three security issues and one bug are now
available for Red Hat Enterprise Linux 6.

The Red Hat Security Response Team has rated this update as having moderate
security impact. Common Vulnerability Scoring System (CVSS) base scores,
which give detailed severity ratings, are available for each vulnerability
from the CVE links in the References section.

Description

The glibc packages provide the standard C and standard math libraries used
by multiple programs on the system. Without these libraries, the Linux
system cannot function properly.

Multiple errors in glibc's formatted printing functionality could allow an
attacker to bypass FORTIFY_SOURCE protections and execute arbitrary code
using a format string flaw in an application, even though these protections
are expected to limit the impact of such flaws to an application abort.
(CVE-2012-3404, CVE-2012-3405, CVE-2012-3406)

This update also fixes the following bug:

• A programming error caused an internal array of nameservers to be only

partially initialized when the /etc/resolv.conf file contained IPv6
nameservers. Depending on the contents of a nearby structure, this could
cause certain applications to terminate unexpectedly with a segmentation
fault. The programming error has been fixed, which restores proper behavior
with IPv6 nameservers listed in the /etc/resolv.conf file. (BZ#837026)

All users of glibc are advised to upgrade to these updated packages, which
contain backported patches to fix these issues.

Solution

Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/knowledge/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.3 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.3 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.3 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.3 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 i386
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.3 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.3 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x

Fixes

• BZ - 826943 - CVE-2012-3406 glibc: printf() unbound alloca() usage in case of positional parameters + many format specs
• BZ - 833703 - CVE-2012-3404 glibc: incorrect size calculation in formatted printing can lead to FORTIFY_SOURCE format string protection bypass
• BZ - 833704 - CVE-2012-3405 glibc: incorrect use of extend_alloca() in formatted printing can lead to FORTIFY_SOURCE format string protection bypass
• BZ - 837026 - libresolv dumps core when IPv6 address in resolv.conf

CVEs

• CVE-2012-3406
• CVE-2012-3405
• CVE-2012-3404

References