Moderate: gdb security and bug fix update

Synopsis

Moderate: gdb security and bug fix update

Type/Severity

Security Advisory: Moderate

Topic

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

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 GNU Debugger (GDB) allows debugging of programs written in C, C++,
Java, and other languages by executing them in a controlled fashion and
then printing out their data.

GDB tried to auto-load certain files (such as GDB scripts, Python scripts,
and a thread debugging library) from the current working directory when
debugging programs. This could result in the execution of arbitrary code
with the user's privileges when GDB was run in a directory that has
untrusted content. (CVE-2011-4355)

With this update, GDB no longer auto-loads files from the current directory
and only trusts certain system directories by default. The list of trusted
directories can be viewed and modified using the "show auto-load safe-path"
and "set auto-load safe-path" GDB commands. Refer to the GDB manual, linked
to in the References, for further information.

This update also fixes the following bugs:

• When a struct member was at an offset greater than 256 MB, the resulting
  bit position within the struct overflowed and caused an invalid memory
  access by GDB. With this update, the code has been modified to ensure that
  GDB can access such positions. (BZ#795424)
  
• When a thread list of the core file became corrupted, GDB did not print
  this list but displayed the "Cannot find new threads: generic error" error
  message instead. With this update, GDB has been modified and it now prints
  the thread list of the core file as expected. (BZ#811648)
  
• GDB did not properly handle debugging of multiple binaries with the
  same build ID. This update modifies GDB to use symbolic links created for
  particular binaries so that debugging of binaries that share a build ID
  now proceeds as expected. Debugging of live programs and core files is
  now more user-friendly. (BZ#836966)
  

All users of gdb 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.

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 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• 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 Power, big endian 6 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

Fixes

• BZ - 703238 - CVE-2011-4355 gdb: object file .debug_gdb_scripts section improper input validation
• BZ - 811648 - Cannot find new threads: generic error
• BZ - 836966 - Backport gdb fix to handle identical binaries via additional build-id symlinks

CVEs

• CVE-2011-4355

References

• https://access.redhat.com/security/updates/classification/#moderate
• http://sourceware.org/gdb/current/onlinedocs/gdb/Auto_002dloading-safe-path.html#Auto_002dloading-safe-path
• http://sourceware.org/gdb/current/onlinedocs/gdb/Auto_002dloading.html#Auto_002dloading