[php-src] Issue #20307: zend_mm_heap corrupted in rebuild_object_properties_internal during GC on PHP 8.4.14

Issue: https://github.com/php/php-src/issues/20307 Author: ruudk ### Description We're experiencing intermittent crashes with zend_mm_heap corrupted errors during PHPUnit test execution on PHP 8.4.14. The crash occurs in the garbage collector while rebuilding object properties. ### PHP Version PHP 8.4.14 ### Operating System Ubuntu 24.04 x86_64 (GitHub Actions runner: depot-ubuntu-24.04) ### Reproduction The crash happens intermittently when running PHPUnit tests with: - APP_DEBUG=1 - Random test order (--order-by=random) - Large test suite (~7748 tests) The crash appears to be related to garbage collection triggered during test execution. ### Backtrace ``` Program terminated with signal SIGABRT, Aborted. #0 __pthread_kill_implementation (no_tid=0, signo=6, threadid=<optimized out>) at ./nptl/pthread_kill.c:44 #1 __pthread_kill_internal (signo=6, threadid=<optimized out>) at ./nptl/pthread_kill.c:78 #2 __GI___pthread_kill (threadid=<optimized out>, signo=signo@entry=6) at ./nptl/pthread_kill.c:89 #3 0x00007f813784527e in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26 #4 0x00007f81378288ff in __GI_abort () at ./stdlib/abort.c:79 #5 0x0000564c8fc0e291 in ?? () #6 0x0000564c8fc0e3a5 in ?? () #7 0x0000564c8fed6244 in _zend_new_array () #8 0x0000564c8ff0a871 in rebuild_object_properties_internal () #9 0x0000564c8fed2249 in zend_gc_collect_cycles () #10 0x0000564c8fed04c8 in ?? () #11 0x0000564c8fecbb00 in execute_ex () #12 0x0000564c8fec1b41 in zend_execute () #13 0x0000564c8ff2d0e6 in zend_execute_script () #14 0x0000564c8fdbe6a8 in php_execute_script_ex () #15 0x0000564c8ff2eff0 in ?? () #16 0x0000564c8fc32a03 in ?? () ``` Full command that crashed: ``` php -d memory_limit=-1 vendor/bin/phpunit --order-by=random --random-order-seed=<seed> ``` ### Analysis The crash occurs during: 1. Garbage collection cycle (zend_gc_collect_cycles) 2. While rebuilding object properties (rebuild_object_properties_internal) 3. When creating a new array (_zend_new_array) 4. PHP's memory manager detects heap corruption and calls abort() ### Relationship to Existing Issues This appears to be related to the systemic GC/destructor issues tracked in #20001. Similar issues were reported in #17866 and #17868, which were supposedly fixed in PHP 8.4.5, but we're seeing this on 8.4.14. ### Configuration - OPcache: Enabled (but disabled for CLI) - JIT: Not enabled - Extensions: Standard Symfony/PHPUnit stack - Memory limit: Unlimited (-1) ### Frequency The crash is intermittent but reproducible when running the full test suite multiple times. It doesn't always occur on the same test. ### Workaround Disabling GC with gc_disable() or zend.enable_gc=0 prevents the crash, confirming it's GC-related. ### Additional Context We've captured core dumps and can provide more detailed debugging information if needed. The crash is blocking our CI pipeline as it occurs randomly during test execution.