(RHSA-2010:0872) Important: glibc security and bug fix update

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

It was discovered that the glibc dynamic linker/loader did not handle the
$ORIGIN dynamic string token set in the LD_AUDIT environment variable
securely. A local attacker with write access to a file system containing
setuid or setgid binaries could use this flaw to escalate their privileges.
(CVE-2010-3847)

It was discovered that the glibc dynamic linker/loader did not perform
sufficient safety checks when loading dynamic shared objects (DSOs) to
provide callbacks for its auditing API during the execution of privileged
programs. A local attacker could use this flaw to escalate their privileges
via a carefully-chosen system DSO library containing unsafe constructors.
(CVE-2010-3856)

Red Hat would like to thank Tavis Ormandy for reporting the CVE-2010-3847
issue, and Ben Hawkes and Tavis Ormandy for reporting the CVE-2010-3856
issue.

This update also fixes the following bugs:

• Previously, the generic implementation of the strstr() and memmem()
  functions did not handle certain periodic patterns correctly and could find
  a false positive match. This error has been fixed, and both functions now
  work as expected. (BZ#643341)

• The “TCB_ALIGNMENT” value has been increased to 32 bytes to prevent
  applications from crashing during symbol resolution on 64-bit systems with
  support for Intel AVX vector registers. (BZ#643343)

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