RHSA-2015:0863 - Security Advisory

Topic

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

Red Hat Product Security 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 libraries (libc), POSIX thread
libraries (libpthread), standard math libraries (libm), and the Name
Server Caching Daemon (nscd) used by multiple programs on the system.
Without these libraries, the Linux system cannot function correctly.

A buffer overflow flaw was found in the way glibc's gethostbyname_r() and
other related functions computed the size of a buffer when passed a
misaligned buffer as input. An attacker able to make an application call
any of these functions with a misaligned buffer could use this flaw to
crash the application or, potentially, execute arbitrary code with the
permissions of the user running the application. (CVE-2015-1781)

It was discovered that, under certain circumstances, glibc's getaddrinfo()
function would send DNS queries to random file descriptors. An attacker
could potentially use this flaw to send DNS queries to unintended
recipients, resulting in information disclosure or data loss due to the
application encountering corrupted data. (CVE-2013-7423)

The CVE-2015-1781 issue was discovered by Arjun Shankar of Red Hat.

This update also fixes the following bug:

• Previously, the nscd daemon did not properly reload modified data when

the user edited monitored nscd configuration files. As a consequence, nscd
returned stale data to system processes. This update adds a system of
inotify-based monitoring and stat-based backup monitoring for nscd
configuration files. As a result, nscd now detects changes to its
configuration files and reloads the data properly, which prevents it from
returning stale data. (BZ#1194149)

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

Solution

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

For details on how to apply this update, refer to:

https://access.redhat.com/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 6.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.6 i386
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.6 i386
• Red Hat Enterprise Linux Server - AUS 6.6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• 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 6.6 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.6 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 6.6 x86_64
• Red Hat Enterprise Linux EUS Compute Node 6.6 x86_64
• Red Hat Enterprise Linux Server - TUS 6.6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x

Fixes

• BZ - 1187109 - CVE-2013-7423 glibc: getaddrinfo() writes DNS queries to random file descriptors under high load
• BZ - 1199525 - CVE-2015-1781 glibc: buffer overflow in gethostbyname_r() and related functions with misaligned buffer

CVEs

• CVE-2015-1781
• CVE-2013-7423

References

• https://access.redhat.com/security/updates/classification/#moderate