Bug #67314 [Opn->Asn]: Segmentation fault in gc_remove_zval_from_buffer

Edit report at https://bugs.php.net/bug.php?id=67314&edit=1 ID: 67314 Updated by: dmitry@php.net Reported by: webm4st0r at gmail dot com Summary: Segmentation fault in gc_remove_zval_from_buffer -Status: Open +Status: Assigned Type: Bug Package: Reproducible crash Operating System: CentOS confirmed PHP Version: 5.5.12 -Assigned To: +Assigned To: dmitry Block user comment: N Private report: N Previous Comments: ------------------------------------------------------------------------ [2014-06-05 11:13:35] arjen at react dot com Easy to reproduce, also crashes with zend.enable_gc=0 Valgrind log: ==3277== Invalid write of size 8 ==3277== at 0x7AF480: gc_remove_zval_from_buffer (zend_gc.h:189) ==3277== by 0x780CA7: _zval_ptr_dtor (zend_execute.h:80) ==3277== by 0x79E427: zend_hash_clean (zend_hash.c:596) ==3277== by 0x8444C4: zend_clean_and_cache_symbol_table (zend_execute.c:1498) ==3277== by 0x844602: zend_leave_helper_SPEC (zend_vm_execute.h:438) ==3277== by 0x7BA477: execute_ex (zend_vm_execute.h:363) ==3277== by 0x79216A: zend_execute_scripts (zend.c:1316) ==3277== by 0x7315F0: php_execute_script (main.c:2506) ==3277== by 0x849F5B: do_cli (php_cli.c:994) ==3277== by 0x4312E6: main (php_cli.c:1378) ==3277== Address 0x0 is not stack'd, malloc'd or (recently) free'd ==3277== ==3277== ==3277== Process terminating with default action of signal 11 (SIGSEGV) ==3277== Access not within mapped region at address 0x0 ==3277== at 0x7AF480: gc_remove_zval_from_buffer (zend_gc.h:189) ==3277== by 0x780CA7: _zval_ptr_dtor (zend_execute.h:80) ==3277== by 0x79E427: zend_hash_clean (zend_hash.c:596) ==3277== by 0x8444C4: zend_clean_and_cache_symbol_table (zend_execute.c:1498) ==3277== by 0x844602: zend_leave_helper_SPEC (zend_vm_execute.h:438) ==3277== by 0x7BA477: execute_ex (zend_vm_execute.h:363) ==3277== by 0x79216A: zend_execute_scripts (zend.c:1316) ==3277== by 0x7315F0: php_execute_script (main.c:2506) ==3277== by 0x849F5B: do_cli (php_cli.c:994) ==3277== by 0x4312E6: main (php_cli.c:1378) ==3277== If you believe this happened as a result of a stack ==3277== overflow in your program's main thread (unlikely but ==3277== possible), you can try to increase the size of the ==3277== main thread stack using the --main-stacksize= flag. ==3277== The main thread stack size used in this run was 8388608. ==3277== ==3277== HEAP SUMMARY: ==3277== in use at exit: 3,398,590 bytes in 18,007 blocks ==3277== total heap usage: 22,264 allocs, 4,257 frees, 3,620,171 bytes allocated ==3277== ==3277== LEAK SUMMARY: ==3277== definitely lost: 32 bytes in 1 blocks ==3277== indirectly lost: 241 bytes in 4 blocks ==3277== possibly lost: 0 bytes in 0 blocks ==3277== still reachable: 3,398,317 bytes in 18,002 blocks ==3277== suppressed: 0 bytes in 0 blocks ==3277== Rerun with --leak-check=full to see details of leaked memory ==3277== ==3277== For counts of detected and suppressed errors, rerun with: -v ==3277== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 3 from 3) ------------------------------------------------------------------------ [2014-05-20 21:22:54] webm4st0r at gmail dot com Description: ------------ I have encountered a reproducible crash on PHP 5.5.0 and greater. This is simple to work around as it just requires that you declare variables properly, but I suspect the engine should not segfault :). This seems to require that a custom error handler be registered. I reported a similar bug a while back that this reminds me of, but may not be related: https://bugs.php.net/bug.php?id=66127 3v4l output: http://3v4l.org/lespU Test script: --------------- <?php function crash() { $notDefined[$i] = 'test'; } function error_handler() { return false; } set_error_handler('error_handler'); crash(); echo "made it once\n"; crash(); echo "ok\n"; Expected result: ---------------- Notice: Undefined variable: i in /in/lespU on line 4 made it once Notice: Undefined variable: i in /in/lespU on line 4 ok Actual result: -------------- Notice: Undefined variable: i in /in/lespU on line 4 made it once Notice: Undefined variable: i in /in/lespU on line 4 Process exited with code 139. ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=67314&edit=1