RHBA-2013:1308 - Bug Fix Advisory

Topic

Updated glibc packages that fix several bugs are now available for Red Hat
Enterprise Linux 5.

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.

This update also fixes the following bugs:

• The library uses the compat_call() function which in turn uses the

getgrent_r() function which is reentrant safe, but not thread safe. As a result,
if multiple threads call getgrent_r() using compat_call(), they may race against
each other, resulting in some groups not being properly reported. With this
update, locking was added to the compat_call() function to prevent multiple
threads from racing. All groups are now properly reported. (BZ#706571)

• A library security mechanism failed to correctly run the initialization

function of dynamically-loaded character conversion routines. Consequently,
glibc could sometimes terminate unexpectedly with a segmentation fault when
attempting to use one dynamically-loaded character conversion routine. The
library security mechanism has been fixed to correctly run the initialization
function. After this update, the aforementioned problem no longer occurs in this
situation. (BZ#816647)

• Various bugs in the wide character version of the fseek() function resulted in

the internal FILE offset field being set incorrectly in wide character streams.
As a result, the offset returned by the ftell() function was incorrect, and
sometimes, data could be overwritten. The ftell() function was fixed to
correctly set the internal FILE offset field for wide characters. The ftell()
and fseek() functions now handle offsets for wide characters correctly.
(BZ#835828)

• A fix to prevent logic errors in various mathematical functions, including

exp(), exp2(), expf(), exp2f(), pow(), sin(), tan(), and rint(), caused by
inconsistent results when the functions were used with the non-default rounding
mode, creates performance regressions for certain inputs. The performance
regressions have been analyzed and the core routines have been optimized to
improve performance. (BZ#861871)

• A defect in the nscd daemon caused it to cache results for DNS entries with a

TTL value of zero. This caused DNS lookups to return stale results. The nscd
daemon has been fixed to correctly respect DNS TTL entries of zero. The nscd
daemon no longer cache DNS entries with a TTL of zero and lookups for those
entries return the correct and current results. (BZ#929035)

• A defect in the library localization routines resulted in unexpected

termination of the application in low-memory conditions. The affected routines
have been fixed to correctly detect and report errors when a low-memory
condition prevents their correct operation. Applications running under
low-memory conditions no longer terminate unexpectedly while calling
localization routines. (BZ#957089)

Users of glibc are advised to upgrade to these updated packages, which fix these
bugs.

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/site/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 5 x86_64
• Red Hat Enterprise Linux Server 5 ia64
• Red Hat Enterprise Linux Server 5 i386
• Red Hat Enterprise Linux Workstation 5 x86_64
• Red Hat Enterprise Linux Workstation 5 i386
• Red Hat Enterprise Linux Desktop 5 x86_64
• Red Hat Enterprise Linux Desktop 5 i386
• Red Hat Enterprise Linux for IBM z Systems 5 s390x
• Red Hat Enterprise Linux for Power, big endian 5 ppc
• Red Hat Enterprise Linux Server from RHUI 5 x86_64
• Red Hat Enterprise Linux Server from RHUI 5 i386

Fixes

• BZ - 706571 - nscd is not reporting all secondary groups in /etc/group
• BZ - 957089 - glibc: a bug in the patch for RHBZ#951493

CVEs

(none)

References

(none)