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Bug #77048 opcache segfault when enabled
Submitted: 2018-10-22 22:41 UTC Modified: 2018-11-11 12:45 UTC
From: chris at policyreporter dot com Assigned: cmb (profile)
Status: No Feedback Package: opcache
PHP Version: 7.2.11 OS: Ubuntu 18.04 LTS
Private report: No CVE-ID: None
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 [2018-10-22 22:41 UTC] chris at policyreporter dot com
Description:
------------
I set up a new server on Ubuntu 18.04 w/ Apache 2.4 and PHP 7.2.11. When attempting to access a Zend Framework site, I noted endless "no response received" errors. When I looked at Apache's error log, I saw a string of seg fault errors:

[Mon Oct 22 20:31:13.154847 2018] [core:notice] [pid 22532] AH00051: child pid 23483 exit signal Segmentation fault (11), possible coredump in /etc/apache2
[Mon Oct 22 20:31:13.157075 2018] [core:notice] [pid 22532] AH00051: child pid 23494 exit signal Segmentation fault (11), possible coredump in /etc/apache2
[Mon Oct 22 20:31:21.168845 2018] [core:notice] [pid 22532] AH00051: child pid 23497 exit signal Segmentation fault (11), possible coredump in /etc/apache2
[Mon Oct 22 20:31:21.168980 2018] [core:notice] [pid 22532] AH00051: child pid 23498 exit signal Segmentation fault (11), possible coredump in /etc/apache2```

After much debugging and troubleshooting, I narrowed the issue down to opcache. If I comment out `zend_extension=opcache.so` and instead put `opcache.enable=0` in /etc/php/7.2/apache2/conf.d/10-opcache.ini and restart apache2, the segfaults cease.

Additionally, if opcache is enabled but the xdebug extension is also enabled, there are no segfaults.


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 [2018-10-23 09:23 UTC] cmb@php.net
-Status: Open +Status: Feedback -Assigned To: +Assigned To: cmb
 [2018-10-23 09:23 UTC] cmb@php.net
Not enough information was provided for us to be able
to handle this bug. Please re-read the instructions at
http://bugs.php.net/how-to-report.php

We either need a reproduce script, or at least a backtrace.
 [2018-10-23 09:32 UTC] nikic@php.net
To rule out one particular cause, you can try setting opcache.optimization_level=0 and see if this avoids the segfaults.
 [2018-11-11 12:45 UTC] cmb@php.net
-Status: Feedback +Status: No Feedback
 [2018-11-11 12:45 UTC] cmb@php.net
No feedback was provided. The bug is being suspended because
we assume that you are no longer experiencing the problem.
If this is not the case and you are able to provide the
information that was requested earlier, please do so and
change the status of the bug back to "Re-Opened". Thank you.
 
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