#30397 [Opn]: Segmentation fault in php_printf

ID: 30397 User updated by: kameshj at fastmail dot fm Reported By: kameshj at fastmail dot fm Status: Open Bug Type: Zend Engine 2 problem Operating System: Any Operating System PHP Version: Irrelevant New Comment: I have drilled this down and found this to be a root cause and did this change and found to be working for the past one week so in my local setup so went ahead and checked in this change. Why should I revert? How long I can wait for someone to respond to my question? If you have any problem with this patch technically please let me know I will revert it. Previous Comments: ------------------------------------------------------------------------ [2004-10-17 17:03:41] derick@php.net As far as I know nobody replied to your question about this change, so please revert it. ------------------------------------------------------------------------ [2004-10-16 12:40:32] tony2001@php.net kameshj at fastmail dot fm: If the bug has been fixed, than the bug report should be closed probably? ------------------------------------------------------------------------ [2004-10-16 12:37:25] kameshj at fastmail dot fm Commited both in 5_0 branch and 5_1 HEAD ------------------------------------------------------------------------ [2004-10-16 12:35:50] kameshj at fastmail dot fm Fixed from hyanantha's account. ------------------------------------------------------------------------ [2004-10-11 16:49:29] kameshj at fastmail dot fm Description: ------------ Startup errors causes the segmentation fault if display_startup_errors is enabled. Reproduce code: --------------- display_startup_errors=On extension=kamesh.so(Any nonexistent module) start apache Segmentation fault will happen inside php_printf. Expected result: ---------------- It should log in a error log that non existent module. But should not seg fault. Actual result: -------------- I could see php_output_activate(TSRMLS_C) getting called from php_module_startup immedeately after php_output_startup. Why is this needed? As each SAPI modules call php_output_activate(TSRMLS_C) explicitly as a part of request startup. Why am I concerned about this? Ans: php_output_activate(TSRMLS_C) sets OG(php_body_write) = php_ub_body_write; which causes calls to php_printf to use php_ub_body_write which depends on SG(request_info) which is null while php_printf is invoked as part of apache startup error(Like Invalid extension/ Non existent extension) logging. This causes segmentation fault. This change seems to have been introduced in version 1.371 of main/main.c by Zeev(3 years and 3 months ago). The comment says, Fix a major thread safety bug in the output mechanism @- Fixed a major memory corruption bug in the thread safe version (Zeev) Can I remove a call to php_output_activate(TSRMLS_C) from php_module_startup? PS:What is the use of display_startup_errors? What does display mean with respect to startup as it might not have any associated request context? ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=30397&edit=1