Bug #78280 [Opn]: _emalloc causes segfaults

Edit report at https://bugs.php.net/bug.php?id=78280&edit=1 ID: 78280 User updated by: grzegorz129 at gmail dot com Reported by: grzegorz129 at gmail dot com Summary: _emalloc causes segfaults Status: Open Type: Bug Package: Reproducible crash Operating System: Linux PHP Version: 7.3.7 Block user comment: N Private report: N New Comment: Some clarifications: - I ruled out hardware problem - this is reproducible on 3 AWS instances as well as 2 physical machines (running Ubuntu on VMWare with Windows host) - System is not pressured into OOM (~40/60GB of physical memory free). The PHP process has memory_limit of 2GB of which it uses ~1.2-1.3GB - The zbacktrace is almost always different while running the code. Originally the error presented itself while throwing an exception, now after couple code changes it usually either happens during Doctrine hydration but also in other places - I tried both with gc enabled as well as gc_disable + gc_collect between big loops - no change Previous Comments: ------------------------------------------------------------------------ [2019-07-12 16:04:53] nikic@php.net Thanks for checking, must be a different problem then. Is this a regression from a recent release? Does this occur under opcache? If this is code callable from CLI, can you run PHP using "USE_ZEND_ALLOC=0 valgrind php script.php" and provide the resulting log? ------------------------------------------------------------------------ [2019-07-12 15:58:49] grzegorz129 at gmail dot com And another ones: https://pastebin.com/06fsMevR I got my 7.3.7 yesterday from github tgz release. I double checked and the path is in the source I compiled. I can try compiling latest master if that helps? ------------------------------------------------------------------------ [2019-07-12 15:47:40] nikic@php.net Where did you get this 7.3.7 release? It was retagged due to a critical opcache bug, and I suspect your build does not include https://github.com/php/php-src/commit/21465ec0e1c1401751b35a21f45f1d57255d5be9. ------------------------------------------------------------------------ [2019-07-12 15:43:31] grzegorz129 at gmail dot com Description: ------------ From the start I have to say I don't have a reproducer which I can share, since problem only demonstrates itself in a large codebase. However, I'm able to consistently reproduce the problem and I was able to gather couple core dumps. - https://pastebin.com/AD7Gtv4k - https://pastebin.com/iG9djuPi - https://pastebin.com/yMNHsgF2 - https://pastebin.com/PEyBwdry - https://pastebin.com/bBjPaAEy The only consistent element I see is the top frames on the chain: _emalloc -> zend_mm_alloc_heap -> zend_mm_alloc_small Test script: --------------- Not available Expected result: ---------------- - Actual result: -------------- Segfault ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=78280&edit=1