RHSA-2012:1097 - Security Advisory

Topic

Updated glibc packages that fix one security issue and one bug are now
available for Red Hat Enterprise Linux 5.

The Red Hat Security Response Team has rated this update as having moderate
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 and standard math libraries used
by multiple programs on the system. Without these libraries, the Linux
system cannot function properly.

It was discovered that the formatted printing functionality in glibc did
not properly restrict the use of alloca(). This could allow an attacker to
bypass FORTIFY_SOURCE protections and execute arbitrary code using a format
string flaw in an application, even though these protections are expected
to limit the impact of such flaws to an application abort. (CVE-2012-3406)

This update also fixes the following bug:

• If a file or a string was in the IBM-930 encoding, and contained the

invalid multibyte character "0xffff", attempting to use iconv() (or the
iconv command) to convert that file or string to another encoding, such as
UTF-8, resulted in a segmentation fault. With this update, the conversion
code for the IBM-930 encoding recognizes this invalid character and calls
an error handler, rather than causing a segmentation fault. (BZ#837896)

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

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/knowledge/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 - 826943 - CVE-2012-3406 glibc: printf() unbound alloca() usage in case of positional parameters + many format specs

CVEs

• CVE-2012-3406

References

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