ID: 29915 Updated by: [EMAIL PROTECTED] Reported By: test dot 007 at seznam dot cz -Status: Open +Status: Feedback Bug Type: Reproducible crash Operating System: any PHP Version: 5CVS-2004-08-31 (dev) New Comment:
Please try using this CVS snapshot: http://snaps.php.net/php5-STABLE-latest.tar.gz For Windows: http://snaps.php.net/win32/php5.0-win32-latest.zip Please provide a short but complete reproduce script if you still expirience this issue. Also, I don't quite understand: you're talking about 5.0.x-CVS, but the patch you provided is against 4.3.x-CVS. Previous Comments: ------------------------------------------------------------------------ [2004-08-31 15:30:07] test dot 007 at seznam dot cz Description: ------------ There's a dangling pointer in TSRM.c: allocate_new_resource(), the last command. After tsrm_mutex_unlock(tsmm_mutex); the (*thread_resources_ptr) is invalid if you're really unlucky. Fix: diff ..\php-4.3.8.orig\TSRM\TSRM.c TSRM\TSRM.c 258a259 > tsrm_tls_entry *new_resource; 261a263 > new_resource = (*thread_resources_ptr); 291c293 < tsrm_new_thread_end_handler(thread_id, &((*thread_resources_ptr)->storage)); --- > tsrm_new_thread_end_handler(thread_id, > &((new_resource)->storage)); Long description: I believe there's a bug even in latest PHP 5, which crashes more probably in debug build, see TSRM/tsrm.c: ts_resource_ex() calls while owning a mutex: allocate_new_resource(&thread_resources->next, thread_id); That should add a new tsrm_tls_entry* thread_resources to the end of the linked list. allocate_new_resource(tsrm_tls_entry **thread_resources_ptr, THREAD_T thread_id) adds a new linked entry (i.e. sets the list tail's next) (*thread_resources_ptr) = (tsrm_tls_entry *) malloc(sizeof(tsrm_tls_entry)); unlock the mutex; tsrm_new_thread_end_handler(thread_id, &((*thread_resources_ptr)->storage)); /* 2nd arg equals to (*thread_resources_ptr) */ If another thread, by accident exactly the thread which has been the last one in the linked list before the allocate_new_resource() called malloc(), and whose "next" entry was set there, calls ts_free_thread(), it free()s the thread_resources of ts_resource_ex() -- in debug build, the (thread_resources->next) vulgo (*thread_resources_ptr) is set to 0xfeeefeee, and the call tsrm_new_thread_end_handler(0xfeeefeee) crashes; in release build, the memory can be used by another malloc() or decommited, but probably, in the very short period this dangling pointer is used, it's not overwritten, thus the code executes almost always without crash. The solution is to store (*thread_resources_ptr) on stack anytimes between malloc() and unlock. Reproduce code: --------------- You need to run multiple threads and call ts_free_thread() from them regularly (is it correct?). You need the thread hash table to be too small so that hash collisions occur. To crash you need the tail of a linked list to call ts_free_thread() at the same time a new tail is added. ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=29915&edit=1
