Bug #77289 [Asn->Csd]: PDO MySQL segfaults with persistent connection

Edit report at https://bugs.php.net/bug.php?id=77289&edit=1 ID: 77289 Updated by: nikic@php.net Reported by: bugs dot php dot net at mundpropaganda dot net Summary: PDO MySQL segfaults with persistent connection -Status: Assigned +Status: Closed Type: Bug Package: PDO MySQL Operating System: Linux 4.14.82 PHP Version: 7.3.0 Assigned To: nikic Block user comment: N Private report: N New Comment: Automatic comment on behalf of lauri.kentta@gmail.com Revision: http://git.php.net/?p=php-src.git;a=commit;h=63c38c9e4907b2d12885db7943b7053efe0d6c60 Log: Fixed bug #77289 Previous Comments: ------------------------------------------------------------------------ [2019-01-08 15:19:10] lauri dot kentta at gmail dot com @nikic, thanks for pointing out those functions. That's exactly what I was looking for. I'll send another patch to use them in pdo_mysql. It works and seems like the right solution. By the way, both functions are used in mysqli as well. ------------------------------------------------------------------------ [2019-01-08 11:09:55] nikic@php.net I think the problem is that the mysqlnd connection has end_psession and restart_psession handlers that are supposed to be called at the end/start of a request respectively. If end_psession were called, it would free the last_message and NULL it. However, it seems that mysqli only calls restart_psession (which also nulls last_message, so probably prevents the worst) and PDO doesn't call either (resulting in what we see here). @dmitry: What do you think about this? I think reverting to use persistent flag for last_message is probably the most pragmatic thing to do here. (There might be ABI concerns though...) ------------------------------------------------------------------------ [2019-01-08 09:37:38] nikic@php.net last_message was changed in https://github.com/php/php-src/commit/a7305eb539596e175bd6c3ae9a20953358c5d677 to be allocated by Zend MM, with the comment that it's not supposed to be used in the next request. I'm not sure if the attached patch is right, or if some use of last_message (or lack of reset somewhere) is at fault here. ------------------------------------------------------------------------ [2019-01-07 19:29:04] lauri dot kentta at gmail dot com Related To: Bug #77312 ------------------------------------------------------------------------ [2019-01-06 21:18:16] bugs dot php dot net at mundpropaganda dot net Hey Lauri, OP here. Just want to say wow and thanks… big time! Your work is greatly appreciated! The other opcache bug I encountered seems already fixed in 7.3.1RC1. Looking fwd to the next patch releases! ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=77289 -- Edit this bug report at https://bugs.php.net/bug.php?id=77289&edit=1