Topic

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

Red Hat Product Security has rated this update as having Critical security
impact. A Common Vulnerability Scoring System (CVSS) base score, which
gives a detailed severity rating, is available from the CVE link 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 stack-based buffer overflow was found in the way the libresolv library
performed dual A/AAAA DNS queries. A remote attacker could create a
specially crafted DNS response which could cause libresolv to crash or,
potentially, execute code with the permissions of the user running the
library. Note: this issue is only exposed when libresolv is called from the
nss_dns NSS service module. (CVE-2015-7547)

This issue was discovered by the Google Security Team and Red Hat.

This update also fixes the following bugs:

• The dynamic loader has been enhanced to allow the loading of more shared

libraries that make use of static thread local storage. While static thread
local storage is the fastest access mechanism it may also prevent the
shared library from being loaded at all since the static storage space is a
limited and shared process-global resource. Applications which would
previously fail with "dlopen: cannot load any more object with static TLS"
should now start up correctly. (BZ#1291270)

• A bug in the POSIX realtime support would cause asynchronous I/O or

certain timer API calls to fail and return errors in the presence of large
thread-local storage data that exceeded PTHREAD_STACK_MIN in size
(generally 16 KiB). The bug in librt has been corrected and the impacted
APIs no longer return errors when large thread-local storage data is
present in the application. (BZ#1301625)

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 6.7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.7 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 6.7 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.7 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 6.7 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.7 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux EUS Compute Node 6.7 x86_64
• RHEL for SAP HANA - Extended Update Support 6.7 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x

Fixes

• BZ - 1293532 - CVE-2015-7547 glibc: getaddrinfo stack-based buffer overflow

CVEs

• CVE-2015-7547

References

• https://access.redhat.com/security/updates/classification/#critical
• https://access.redhat.com/articles/2161461