Description:
------------
I am afraid that I don't have the actual PHP code at short hand.
However, Apache segfaults when I try to log into my Horde Webmail application (running 5.12). After the segfault I cannot login any more and I get a blank page and sometimes an 500 error message shown. Restarting the webserver helps, but after logout and relogin the problem persists.

This problem exists at least since PHP 5.4.20 because thats the version I have started with. I don't know if this problem/bug exists also in previous 5.4 versions.

Upgrading to 5.5.4 solved my problems, but I would rather like to stick to 5.4

Actual result:
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(gdb) run -DSSL -X -f /etc/httpd/conf/httpd.conf
Starting program: /usr/sbin/httpd -DSSL -X -f /etc/httpd/conf/httpd.conf
[Thread debugging using libthread_db enabled]
Detaching after fork from child process 10455.
Detaching after fork from child process 10456.
Detaching after fork from child process 10473.
Detaching after fork from child process 10474.
Detaching after fork from child process 10475.
[New Thread 0x7fffd2ffb700 (LWP 10490)]
[Thread 0x7fffd2ffb700 (LWP 10490) exited]

Program received signal SIGSEGV, Segmentation fault.
0x00007fffec0eee83 in instanceof_function_ex () from /etc/httpd/modules/libphp5.so
(gdb) bt
#0  0x00007fffec0eee83 in instanceof_function_ex () from /etc/httpd/modules/libphp5.so
#1  0x00007fffec0eeebb in instanceof_function_ex () from /etc/httpd/modules/libphp5.so
#2  0x00007fffec0eeebb in instanceof_function_ex () from /etc/httpd/modules/libphp5.so
#3  0x00007fffec16cd25 in ?? () from /etc/httpd/modules/libphp5.so
#4  0x00007fffec160fe8 in execute () from /etc/httpd/modules/libphp5.so
#5  0x00007fffec0ec0dc in zend_call_function () from /etc/httpd/modules/libphp5.so
#6  0x00007fffec039917 in ?? () from /etc/httpd/modules/libphp5.so
#7  0x00007fffec17389c in ?? () from /etc/httpd/modules/libphp5.so
#8  0x00007fffec160fe8 in execute () from /etc/httpd/modules/libphp5.so
#9  0x00007fffec0ec0dc in zend_call_function () from /etc/httpd/modules/libphp5.so
#10 0x00007fffec10fa57 in zend_call_method () from /etc/httpd/modules/libphp5.so
#11 0x00007fffec11d20d in zend_std_call_user_call () from /etc/httpd/modules/libphp5.so
#12 0x00007fffec17389c in ?? () from /etc/httpd/modules/libphp5.so
#13 0x00007fffec160fe8 in execute () from /etc/httpd/modules/libphp5.so
#14 0x00007fffec0f6f20 in zend_execute_scripts () from /etc/httpd/modules/libphp5.so
#15 0x00007fffec099cb8 in php_execute_script () from /etc/httpd/modules/libphp5.so
#16 0x00007fffec1a2285 in ?? () from /etc/httpd/modules/libphp5.so
#17 0x00007ffff7fd6bb0 in ap_run_handler ()
#18 0x00007ffff7fda46e in ap_invoke_handler ()
#19 0x00007ffff7fe5b30 in ap_process_request ()
#20 0x00007ffff7fe29a8 in ?? ()
#21 0x00007ffff7fde6b8 in ap_run_process_connection ()
#22 0x00007ffff7fea977 in ?? ()
#23 0x00007ffff7feac46 in ?? ()
#24 0x00007ffff7feb293 in ap_mpm_run ()
#25 0x00007ffff7fc2900 in main ()