Fixed PHP SEGV by not writing to shared memory for zend_class_entry. #9995
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Fixes: #9446
The root cause of the SEGV was that we were mutating
zend_class_entry.create_objectAs of PHP 8.1, it appears thatzend_class_entrystructs for PHP classes are shared between PHP processes when using php-fpm and opcache. This means that writes tozend_class_entry.create_objectin one process will be visible in another process, which violated our assumption that such writes reads and writes were single-threaded.The fix was to stop mutating
zend_class_entry.create_object, instead mutating a member of ourPROTOBUF_G()struct.Unfortunately the setup to reproduce this is somewhat involved, so there is no test at the moment. I tested and verified the fix locally on my machine.