Public bug reported:
In Ubuntu 8.10 (gcc 4.3.2-1ubuntu12) and Ubuntu 7.10 there is a problem with
thread cancellation, stack unwinding and shared libraries. If pthread_cancel is
called in the library, a segmentation fault occurs. For static linkage the
problem does not occur and the thread is canceled as expected.
In the attachment you can find a demo application reproducing the problem. It
consists of an Makefile and the source files:
main.cpp
thread_test_lib.h - library interface
thread_test_lib.cpp - library source
If you invoke make the shared library libthread_test_lib.so and the application
thread_test are built. Make also generates thread_test_static which is the same
application, but statically linked.
The library provides the functions thread_setup() to create an internal
task and thread_cleanup() to cancel the task.
When thread_test is executed a segmentation fault occurs:
./thread_test
thread_setup()
run_thread::task() started
thread_cleanup()
Segmentation fault (core dumped)
According to the core dump the segmentation fault is inside task().
It can be observed that no segmentation fault occurs when
- ./thread_test_static is called instead of ./thread_test
- the line "std::string s..." inside task() (see thread_test_lib.cpp) is
commented out
- usleep() in task() is replaced by sleep() or pthread_testcancel
- usleep() in task() is called indirectly via a wrapper function
Any help is appreciated.
Franz Hollerer
ProblemType: Bug
Architecture: i386
DistroRelease: Ubuntu 8.10
Package: firefox 3.0.14+build2+nobinonly-0ubuntu0.8.10.1
PackageArchitecture: all
ProcEnviron:
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
LANG=de_AT.UTF-8
SHELL=/bin/bash
SourcePackage: firefox-3.0
Uname: Linux 2.6.27-14-generic i686
** Affects: ubuntu
Importance: Undecided
Status: New
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pthread_cancel segfault when used in shared library
https://bugs.launchpad.net/bugs/455808
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