RHBA-2014:1534 - Bug Fix Advisory

Topic

Updated gdb packages that fix several bugs and add one enhancement are now
available for Red Hat Enterprise Linux 6.

Description

The gdb packages provide the GNU Debugger (GDB) to debug programs written in C,
C++, Java, and other languages by executing them in a controlled fashion and
then printing out their data.

This update fixes the following bugs:

• Previously, when the users tried to debug certain core dump files generated

from multi-threaded applications, GDB was unable to handle correctly specific
situations, for example, when a referenced DWARF Compilation Unit was aged out.
As a consequence, performing the "thread apply all bt" command to display a
backtrace of all threads could cause GDB to terminate unexpectedly. A patch has
been provided to fix this bug, and GDB no longer crashes in this scenario.
(BZ#1104587)

• Previously, when executing the signal handling code, GDB was calling certain

non-reentrant functions, such as the calloc() function. This could sometimes
result in a deadlock situation. To avoid deadlocks in this scenario, the
relevant GDB code has been modified to handle non-reentrant functions correctly.
(BZ#913146)

• Previously, due to a bug in a specific function in the support for Python, if

a Python script read a memory region from the program that was being debugged,
and the reference to the memory region became out of scope, GDB did not
deallocate the memory. As a consequence, this led to a memory leak, which was
particularly significant in memory-intensive scenarios. A patch has been
applied, and GDB now frees the acquired memory correctly. (BZ#1007614)

• Prior to this update, GDB did not add the necessary offsets when dealing with

bit fields inside nested instances of the struct data type. Consequently, when
the user tried to set the value of a bit field that was declared inside such a
data structure, GDB was unable to calculate it correctly. With this update, GDB
calculates the values of bit fields inside nested data structures correctly.
(BZ#903734)

• Previously, GDB was unable to correctly access Thread Local Storage (TLS) data

on statically linked binaries. Consequently, the user could not inspect TLS data
on the program being debugged if the program was linked statically. This bug has
been fixed, and users can now inspect TLS data on statically linked binaries as
expected. (BZ#1080656)

• Prior to this update, GDB incorrectly handled symbolic links related to

build-id files. As a consequence, when the user tried to debug core dump files
generated from programs that were not installed on the system, GDB printed
misleading error messages instructing the user to run incorrect commands to
install the binary files. Subsequently, the suggested commands did not fully
work and the program package was not correctly installed. This bug has been
fixed, and GDB now issues a message containing correct commands to install the
necessary binary files. (BZ#981154)

In addition, this update adds the following enhancement:

• This update adds the "$_exitsignal" internal variable to GDB. Now, when

debugging a core dump file of a program that was killed by a signal,
"$_exitsignal" provides the signal number to the user. (BZ#971849)

Users of gdb are advised to upgrade to these updated packages, which fix these
bugs and add this enhancement.

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/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 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
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension (for IBM z Systems) 6 s390x

Fixes

• BZ - 971849 - Add $_signo convenience variable
• BZ - 981154 - gdb gives highly misleading error when debuginfo pkg is present, but not corresponding binary pkg
• BZ - 1007614 - memory leak in infpy_read_memory()
• BZ - 1080656 - [RHEL6] Can't access TLS variables in statically linked binaries

CVEs

(none)

References

(none)