6.8 - RHSA-2016:0175

Problem Description:

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.

2. Relevant releases/architectures:

Red Hat Enterprise Linux Desktop (v. 6) - i386, x86_64 Red Hat Enterprise Linux Desktop Optional (v. 6) - i386, x86_64 Red Hat Enterprise Linux HPC Node (v. 6) - x86_64 Red Hat Enterprise Linux HPC Node Optional (v. 6) - x86_64 Red Hat Enterprise Linux Server (v. 6) - i386, ppc64, s390x, x86_64 Red Hat Enterprise Linux Server Optional (v. 6) - i386, ppc64, s390x, x86_64 Red Hat Enterprise Linux Workstation (v. 6) - i386, x86_64 Red Hat Enterprise Linux Workstation Optional (v. 6) - i386, x86_64

3. 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.

4. 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

5. Bugs fixed (https://bugzilla.redhat.com/):

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