From: emiel dot mols at gmail dot com Operating system: Irrelevant PHP version: 5.5Git-2013-04-03 (snap) Package: Reproducible crash Bug Type: Bug Bug description:debug_backtrace in set_error_handler corrupts zend heap: segfault
Description: ------------ So I thought the other day it might be convenient to grab a stack trace in, you know, the place errors are handled. Apparently, PHP thinks this is a terrible idea. The exact cause is unclear, but I've managed to create a decently small test case that segfaults both on Debian PHP 5.4.4 and Darwin PHP 5.5 nightly. In the attached test script, the call to x() should generate an error, because accessing a string as associative array is forbidden. - the segfault occurs in native _zend_mm_free_int - only able to replicate when there's a function call on the PHP stack - it appears debug_backtrace is only corrupting the stack -- the call to print_r() initiates the segfault. - i've seen $y change every access (eg containing random other variables, or just random heap garbage). - in narrowing down the specific case, I've also often seen messages along the lines of "mm stack corrupt" Core dumps can be found at: - Debian: http://db.tt/aA5wAx7a (16MB) - Darwin: http://db.tt/gxZrP8Pa (400MB) Test script: --------------- <?php set_error_handler(function() { debug_backtrace(); }); function x($s) { $s['a'] = 1; }; $y = '1'; x($y); print_r($y); Expected result: ---------------- Being able to use debug_backtrace() in error handlers. Actual result: -------------- A corrupt heap, resulting in a freaking segfault. -- Edit bug report at https://bugs.php.net/bug.php?id=64578&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=64578&r=trysnapshot54 Try a snapshot (PHP 5.3): https://bugs.php.net/fix.php?id=64578&r=trysnapshot53 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=64578&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=64578&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=64578&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=64578&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=64578&r=needscript Try newer version: https://bugs.php.net/fix.php?id=64578&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=64578&r=support Expected behavior: https://bugs.php.net/fix.php?id=64578&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=64578&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=64578&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=64578&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=64578&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=64578&r=dst IIS Stability: https://bugs.php.net/fix.php?id=64578&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=64578&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=64578&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=64578&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=64578&r=mysqlcfg