Segfaults in php agent module / elasticApmZendThrowExceptionHookImpl()

[keeshoekzema]

Describe the bug
When using the apm-agent-php module on a busy server, the agent sometimes crashes with a segfault.

To Reproduce
(Un)fortunately, the error doesn't appear very often. But it seems to be a recursive loop. This one was caught twice in ~3 days
My relevant configuration:
elastic_apm.server_url="http://localhost:8200"
elastic_apm.transaction_ignore_urls=/healthcheck*
elastic_apm.transaction_sample_rate=0.1
elastic_apm.profiling_inferred_spans_enabled=true
elastic_apm.verify_server_cert = false

I'm using php8.1 and apm-agent-php 1.8.1

Expected behavior
No crash.

A gdb bt on the generated core shows:

Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x00007f96236c8c0c in elasticApmZendThrowExceptionHookImpl () from /opt/elastic/apm-agent-php/extensions/elastic_apm-20210902.so
[Current thread is 1 (Thread 0x7f962b638c40 (LWP 1937845))]
#0  0x00007f96236c8c0c in elasticApmZendThrowExceptionHookImpl () from /opt/elastic/apm-agent-php/extensions/elastic_apm-20210902.so
#1  0x00007f96236c91ec in elasticApmZendThrowExceptionHook () from /opt/elastic/apm-agent-php/extensions/elastic_apm-20210902.so
#2  0x00007f96236c9208 in elasticApmZendThrowExceptionHook () from /opt/elastic/apm-agent-php/extensions/elastic_apm-20210902.so
#3  0x00007f96236c9208 in elasticApmZendThrowExceptionHook () from /opt/elastic/apm-agent-php/extensions/elastic_apm-20210902.so
#4  0x00007f96236c9208 in elasticApmZendThrowExceptionHook () from /opt/elastic/apm-agent-php/extensions/elastic_apm-20210902.so
[.. several minutes later..]
#261670 0x00007f96236c9208 in elasticApmZendThrowExceptionHook () from /opt/elastic/apm-agent-php/extensions/elastic_apm-20210902.so
#261671 0x00007f96236c9208 in elasticApmZendThrowExceptionHook () from /opt/elastic/apm-agent-php/extensions/elastic_apm-20210902.so
#261672 0x00007f962a5250f4 in zend_throw_exception_internal () from /usr/lib/apache2/modules/libphp8.1.so
#261673 0x00007f962a5251ff in ?? () from /usr/lib/apache2/modules/libphp8.1.so
#261674 0x00007f962a525297 in zend_throw_exception () from /usr/lib/apache2/modules/libphp8.1.so
#261675 0x00007f962a511922 in zend_value_error () from /usr/lib/apache2/modules/libphp8.1.so
#261676 0x00007f962a504b4e in ?? () from /usr/lib/apache2/modules/libphp8.1.so
#261677 0x00007f962a632418 in ?? () from /usr/lib/apache2/modules/libphp8.1.so
#261678 0x00007f962a759ae9 in execute_ex () from /usr/lib/apache2/modules/libphp8.1.so
#261679 0x00007f962a75cd8d in zend_execute () from /usr/lib/apache2/modules/libphp8.1.so
#261680 0x00007f962a6ec845 in zend_execute_scripts () from /usr/lib/apache2/modules/libphp8.1.so
#261681 0x00007f962a68968a in php_execute_script () from /usr/lib/apache2/modules/libphp8.1.so
#261682 0x00007f962a7d5690 in ?? () from /usr/lib/apache2/modules/libphp8.1.so
#261683 0x000055ecc2b17ae8 in ap_run_handler ()
#261684 0x000055ecc2b18096 in ap_invoke_handler ()
#261685 0x000055ecc2b30863 in ap_process_async_request ()
#261686 0x000055ecc2b30a32 in ap_process_request ()
#261687 0x000055ecc2b2cac6 in ?? ()
#261688 0x000055ecc2b21828 in ap_run_process_connection ()
#261689 0x00007f962b557997 in ?? () from /usr/lib/apache2/modules/mod_mpm_prefork.so
#261690 0x00007f962b557c9a in ?? () from /usr/lib/apache2/modules/mod_mpm_prefork.so
#261691 0x00007f962b558a18 in ?? () from /usr/lib/apache2/modules/mod_mpm_prefork.so
#261692 0x000055ecc2af9488 in ap_run_mpm ()
#261693 0x000055ecc2af1499 in main ()

[intuibase]

Hey @keeshoekzema

Could you please share a core dump file with us?

I implemented a script which will help to archive a core dump and all dependencies needed to analyze it on different machine that it crashed.

You can find a script crash_collector.sh here:
https://github.com/intuibase/core-dump-collector

Please remember that core dump file may contain a lot of sensitive data, like tokens, sessions data, passwords - please don't publish it to public but rather contact us how to deliver it.

Best regards,
Pawel

[keeshoekzema]

Hello Pawel,

I have the files, where do you want them? You can contact me at kees at tweakers.net

[intuibase]

Hey @keeshoekzema

Fix was included in new release, could you please update to 1.8.4 and verify if it solved issue for you?

Best regards,
Pawel

[intuibase]

Hey @keeshoekzema
Issue was fixed with 1.8.4 release. Please update agent and verify if it solves issue for you.
Best regards,
Pawel