Bug #79646 [Com]: Segmentation fault in garbage collector

Edit report at https://bugs.php.net/bug.php?id=79646&edit=1 ID: 79646 Comment by: enumag at gmail dot com Reported by: enumag at gmail dot com Summary: Segmentation fault in garbage collector Status: Open Type: Bug Package: Scripting Engine problem Operating System: Alpine PHP Version: 7.4.7 Block user comment: N Private report: N New Comment: The command I used this time: USE_ZEND_ALLOC=0 valgrind --tool=memcheck --num-callers=30 --log-file=valgrind.txt --suppressions=php.supp php vendor/bin/phpunit Previous Comments: ------------------------------------------------------------------------ [2020-06-15 12:30:45] enumag at gmail dot com @nikic Check this one please. https://gist.github.com/enumag/329cbe88c5e77c5cc5be74aafa330ba8 ------------------------------------------------------------------------ [2020-06-15 09:15:18] enumag at gmail dot com I can use https://github.com/wodby/base-php docker image for that. Did it before to get the gdb stacktrace. Let me try... ------------------------------------------------------------------------ [2020-06-15 09:04:52] nikic@php.net Thanks! The first invalid read is: ==182== Invalid read of size 16 ==182== at 0xBDF97E1: ??? ==182== by 0xA36A9C7: ??? ==182== by 0xA36A9C7: ??? ==182== by 0xA36A9F2: ??? ==182== by 0x4A8312F: ??? ==182== by 0xA36A9C7: ??? ==182== Address 0xa36a9ef is 63 bytes inside a block of size 72 alloc'd ==182== at 0x489F72A: malloc (vg_replace_malloc.c:309) ==182== by 0x5D30B8: __zend_malloc (in /usr/local/bin/php) ==182== by 0x53ACA6: ??? (in /usr/local/bin/php) ==182== by 0x540AA6: ??? (in /usr/local/bin/php) ==182== by 0x5411E6: ??? (in /usr/local/bin/php) ==182== by 0x67BF73: execute_ex (in /usr/local/bin/php) ==182== by 0x5ED108: zend_call_function (in /usr/local/bin/php) ==182== by 0x617373: zend_call_method (in /usr/local/bin/php) ==182== by 0x4E352A: ??? (in /usr/local/bin/php) ==182== by 0x5ED026: zend_call_function (in /usr/local/bin/php) ==182== by 0x617373: zend_call_method (in /usr/local/bin/php) ==182== by 0x6178BA: zend_user_it_rewind (in /usr/local/bin/php) Unfortunately most debug symbols are missing, so we don't actually see where the invalid read occurs :( Is it possible to install some kind of -dbg / -dbgsym package for PHP on your system? ------------------------------------------------------------------------ [2020-06-15 09:00:39] enumag at gmail dot com Okay, I ran USE_ZEND_ALLOC=0 valgrind --suppressions=php.supp php vendor/bin/phpunit 2> valgrind.txt with the php.supp file you provided. Here is the result: https://gist.github.com/enumag/42402fcc05d9a404656f50a51fb98d2b Please let me know if it helps. ------------------------------------------------------------------------ [2020-06-15 07:47:41] nikic@php.net I can't really do anything here without a way to reproduce. GC issues are always tricky, and "something related to generator GC is broken" is not enough to go on :( You can try running PHP under valgrind, using something like USE_ZEND_ALLOC=0 valgrind php ...args optionally with --suppressions=php.supp from https://gist.github.com/nikic/8d404c6799a1532b0c10280f5e57a888 to reduce noise. That might give us a better idea of the root cause (which may have nothing to do with GC itself). ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=79646 -- Edit this bug report at https://bugs.php.net/bug.php?id=79646&edit=1