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Updated gdb packages that fix several bugs and add one enhancement are now available for Red Hat Enterprise Linux 6.
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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
In addition, this update adds the following
- 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.
Users of gdb are advised to upgrade to these updated packages, which fix these bugs and add this enhancement.