Bug #69446 [NEW]: GC leak relating to removal of nested data after dtors run

From: nikic Operating system: PHP version: master-Git-2015-04-14 (Git) Package: Scripting Engine problem Bug Type: Bug Bug description:GC leak relating to removal of nested data after dtors run Description: ------------ This issue is only obvious when freeing of the object store is disabled - otherwise the leaks will be hidden. Here is a patch to disable it: https://gist.github.com/nikic/2ccbc61c407d5e807781 The following script will leak: <?php $bar = NULL; class bad { public function __destruct() { global $bar; $bar = $this; $bar->y = new stdClass; } } $foo = new stdClass; $foo->foo = $foo; $foo->bad = new bad; $foo->bad->x = new stdClass; unset($foo); gc_collect_cycles(); The following script will also leak: <?php $bar = NULL; class bad { public $_private = array(); public function __construct() { $this->_private[] = 'php'; } public function __destruct() { global $bar; $bar = $this; } } $foo = new stdclass; $foo->foo = $foo; $foo->bad = new bad; unserialize(serialize($foo)); //unset($foo); gc_collect_cycles(); var_dump($bar); I have not been able to figure out how to stop the leak in both cases. The fundamental issue seems to be that gc_remove_nested_data does not decrement the refcount to compensate the incref that occurs in gc_collect_roots. -- Edit bug report at https://bugs.php.net/bug.php?id=69446&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=69446&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=69446&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=69446&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=69446&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=69446&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=69446&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=69446&r=needscript Try newer version: https://bugs.php.net/fix.php?id=69446&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=69446&r=support Expected behavior: https://bugs.php.net/fix.php?id=69446&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=69446&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=69446&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=69446&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=69446&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=69446&r=dst IIS Stability: https://bugs.php.net/fix.php?id=69446&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=69446&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=69446&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=69446&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=69446&r=mysqlcfg