Bug #12270 Updated: php4ts.dll crashes due to null-pointer assignment on shutdown

ID: 12270 Updated by: php-bugs@lists.php.net Reported By: zimpel@t-online.de -Status: Feedback +Status: No Feedback Bug Type: Reproducible crash Operating System: Win32 PHP Version: 4.0.6 New Comment: No feedback was provided for this bug for over a month, so it is being suspended automatically. If you are able to provide the information that was originally requested, please do so and change the status of the bug back to "Open". Previous Comments: ------------------------------------------------------------------------ [2002-02-03 20:19:29] yohgaki@php.net Could you try 4.1.1? ------------------------------------------------------------------------ [2001-07-22 15:30:06] zeev@php.net The fix is not valid - p->pLast cannot be NULLif everything works right - i.e., the bug is elsewhere. Do you have a script that reproduces this problem (preferably with the CGI version of PHP)? ------------------------------------------------------------------------ [2001-07-20 03:02:45] zimpel@t-online.de The crash may be only reproducible in release builds with activated bcmath. (In debug builds the Zend efree() function returns prior actual freeing something, if the thread which calls efree() isn't the thread which original allocated the resource). The "call stack" of this issue is: php_module_shutdown_wrapper() // pi3web_sapi.c php_module_shutdown() // main.c zend_shutdown() // zend.c zend_hash_destroy(&module_registry) // zend_hash.c pefree(ht->arBuckets, ht->persistent) // zend_hash.c ... PHP_MSHUTDOWN_FUNCTION(bcmath) // bcmath.c bc_free_num (num) // init.c, the global bcnum value is _two_ efree ((*num)->n_ptr); // zend_alloc.c In efree() the code in macro REMOVE_POINTER_FROM_LIST() crashes #define REMOVE_POINTER_FROM_LIST(p) \ if (!p->persistent && p==AG(head)) { \ AG(head) = p->pNext; \ } else if (p->persistent && p==AG(phead)) { \ AG(phead) = p->pNext; \ } else { \ p->pLast->pNext = p->pNext; \ } \ if (p->pNext) { \ p->pNext->pLast = p->pLast; \ } The reason of the crash is } else { \ p->pLast->pNext = p->pNext; \ if the pointer pLast == NULL. This is true for the last allocated persistent resource. This code is only called when bcmath performs shutdown, because in other calls of efree() the condition p==AG(head) seems to be always true. A probable fix is: } else if (p->pLast) { \ p->pLast->pNext = p->pNext; \ --- regards, Holger Zimmermann ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=12270&edit=1