Bug #68063 [PATCH]: Empty session IDs do still start sessions

Edit report at https://bugs.php.net/bug.php?id=68063&edit=1 ID: 68063 Patch added by: yohgaki@php.net Reported by: mail at thomasbachem dot com Summary: Empty session IDs do still start sessions Status: Analyzed Type: Bug Package: Session related PHP Version: 5.5.17 Assigned To: yohgaki Block user comment: N Private report: N New Comment: The following patch has been added/updated: Patch Name: bug68063.patch Revision: 1452637734 URL: https://bugs.php.net/patch-display.php?bug=68063&patch=bug68063.patch&revision=1452637734 Previous Comments: ------------------------------------------------------------------------ [2016-01-12 22:27:21] yohgaki@php.net Fix is committed already, but it's not appropriate. if (PS(id) && !strlen(PS(id))) { php_error_docref(NULL TSRMLS_CC, E_WARNING, "Cannot start session with empty session ID"); RETURN_FALSE; } The reason why session ID became empty is browser's cookie handling. To workaround this, session module should keep old session ID for a while. https://wiki.php.net/rfc/precise_session_management Session module should not raise error, but generate new when session ID cookie became empty. ------------------------------------------------------------------------ [2015-06-29 21:26:18] yohgaki@php.net It seems I shouldn't raise error here. Some clients send empty session ID sometimes in rare case. It's probably due to race condition by session_regenerate_id(true). I got report this case from more than 10k RPM site. One possible solution is create new session ID automatically when session ID is empty. Another possible resolution is to implement lazy destruction of session data and not deleting old session ID immediately. Related to https://bugs.php.net/bug.php?id=69127 Re-opened this bug for the time being. ------------------------------------------------------------------------ [2015-02-03 04:51:34] yohgaki@php.net Automatic comment on behalf of yohgaki Revision: http://git.php.net/?p=php-src.git;a=commit;h=853ae39d6ea6a4d2ce95098744e481a1e8573ad8 Log: Fixed bug #68063 Empty session IDs do still start sessions ------------------------------------------------------------------------ [2014-09-20 11:15:06] mail at thomasbachem dot com Description: ------------ If an empty session ID is given to PHP (e.g. a cookie with "PHPSESSID=; path=/" or simply by calling "session_id('')"), session_start() will throw an E_WARNING error from the default session handler ("session_start(): The session id is too long or contains illegal characters, valid characters are a-z, A-Z, 0-9 and '-,'") but still returns true and starts a session. Now session_id() returns '' (the manual states this only happens if there is no current session), but the session was still started, and custom session save handlers are given an empty session ID. If they don't handle that case, a session handler may then actually save session data for an empty session ID. Even the examples from the manual (http://php.net/manual/en/function.session-set-save-handler.php) don't check for an empty session ID. Test script: --------------- <?php // Could also be set with a cookie like "PHPSESSID=; path=/" session_id(''); // Will still start the session and return true var_dump(session_start()); // Returns an empty string var_dump(session_id()); Expected result: ---------------- I would expect session_start() to regenerate a session ID OR to fail, return false and not trigger any session save handlers. Actual result: -------------- Warning: session_start(): The session id is too long or contains illegal characters, valid characters are a-z, A-Z, 0-9 and '-,' in emptysession.php on line 5 boolean true string '' (length=0) Warning: Unknown: The session id is too long or contains illegal characters, valid characters are a-z, A-Z, 0-9 and '-,' in Unknown on line 0 Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct () in Unknown on line 0 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=68063&edit=1