RHBA-2013:1317 - Bug Fix Advisory

Topic

Updated ltrace packages that fix several bugs are now available for Red Hat
Enterprise Linux 5.

Description

The ltrace utility is a debugging program that runs a specified command until
the command exits. While the command is executing, ltrace intercepts and records
both the dynamic library calls called by the executed process and the signals
received by the executed process. The ltrace utility can also intercept and
print system calls executed by the process.

This update fixes the following bugs:

• On a system with the Itanium architecture, a SIGILL signal was occasionally

delivered as a valid signal that informed the ltrace utility about events in a
traced binary. However, ltrace misinterpreted the SIGILL signal as a signal
delivered to the traced binary. With this update, ltrace handles SIGILL as
expected. (BZ#239057)

• When tracing a process with many threads, the traced process was often killed

as the threads ran into breakpoints that could not be handled by the ltrace
utility. With this update, ltrace attaches to the newly created threads and
carefully handles the breakpoints so that tracing events are not missed.
Note that when ltrace attached to a running process, that process could have
been detached from with the instruction pointer pointed to mid-instruction, or
with pending events, which would kill the process. This update improves the
detach logic so that the process is left in a consistent state before detaching.
(BZ#526007)

• Due to a bug in the logic of tracing processes, the ltrace utility missed

tracing events in forked processes on PowerPC systems. The logic of tracing
processes that fork or clone has been improved and ltrace now works as expected.
(BZ#639947)

• On PowerPC systems, the "-e" option did not work correctly. Consequently, when

the option was given with a symbol name that did not match any of the symbols in
the traced binary, the ltrace utility terminated unexpectedly. This update
provides a patch to fix this bug and ltrace no longer crashes in the described
scenario. (BZ#754096)

• Previously, the ltrace utility did not support PIE (Position Independent

Executables) binaries, which are linked similarly to shared libraries, and
processes. Consequently, addresses found in images of those binaries needed
additional adjustment for the actual address where the binary was loaded during
the process startup. With this update, the support for PIE binaries and
processes has been added and ltrace now handles the additional processing for
the PIE binaries correctly. (BZ#868281)

• When copying internal structures after cloning a process, the ltrace utility

did not copy a string containing a path to an executable properly. This behavior
led to errors in heap management and could cause ltrace to terminate
unexpectedly. The underlying source code has been modified and ltrace now copies
memory when cloning traced processes correctly. (BZ#890961)

Users of ltrace are advised to upgrade to these updated packages, which fix
these bugs.

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/site/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 - 526007 - ltrace cannot properly handle multi-threaded processes
• BZ - 639947 - testsuite: FAIL: '^\[pid [0-9]*\][ \t]*(printf|puts)' in ./ltrace.minor/trace-fork.ltrace for 1 times ,should be 2
• BZ - 754096 - ltrace crashes on PowerPC if tracing is limited by `-e' to event not present in trace

CVEs

(none)

References

(none)