php.net |  support |  documentation |  report a bug |  advanced search |  search howto |  statistics |  random bug |  login
Bug #77935 Crash in mysqlnd_fetch_stmt_row_cursor when calling an SP with a cursor
Submitted: 2019-04-24 14:03 UTC Modified: -
From: rh at tfli dot co dot uk Assigned:
Status: Open Package: MySQLi related
PHP Version: 7.3.4 OS: Windows 10 (64Bit)
Private report: No CVE-ID: None
Have you experienced this issue?
Rate the importance of this bug to you:

 [2019-04-24 14:03 UTC] rh at tfli dot co dot uk
Description:
------------
Good Afternoon,

When you connect to a Maria Server (10.3) using the mysqli extension, then if you prepare a statement which calls a stored procedure; where that stored procedure uses opens a cursor on the server and returns a result set, when you try and fetch the result set as a mysqli_result, PHP will crash with a access violation.

- I assume this will also apply to MySQL.
- If you try and fetch() the result set from the mysqli_stmt object, you get a warning about packets being out of order and no data. I believe the cause is the same problem.
- The problem seems to be related that the COM_STMT_EXECUTE response has a server flag marking 'SERVER_STATUS_CURSOR_EXISTS' as Set when a cursor is used in the stored procedure. This flag is meant to be used with COM_STMT_FETCH, and I believe this to be a server bug (which will be reported to MariaDB as well).
- When that flag is set and you try to call a function like fetch_all on a mysqli_result retrieved from the mysqli_stmt; when mysqlnd_fetch_stmt_row_cursor is called, param which is passed in is not the mysqli_stmt as expected (WinDbg revealed for me that it was the PHP.ini file).
- In my tests, the bytes that were thought to be the statement's status were 0, so it thought the status was MYSQLND_STMT_INITTED. However, when it tried to set the connection error to CR_COMMANDS_OUT_OF_SYNC, what was thought to be the connection pointed to an invalid memory location, throwing the access violation.

Can the SERVER_STATUS_CURSOR_EXISTS be ignored in the COM_STMT_EXECUTE response?

Test script:
---------------
/* SQL Script:
DELIMITER $$

CREATE
    PROCEDURE `testSp`()
	BEGIN
		DECLARE `cur` CURSOR FOR SELECT 1;
		OPEN `cur`;
		CLOSE `cur`;
		SELECT 1;
	END$$

DELIMITER ; */
<?PHP
$dbHost = '';
$dbUsername = '';
$dbPassword = '';
$dbName = "";
$dbConn			= new mysqli($dbHost, $dbUsername, $dbPassword, $dbName);
$prepopReturnStmt		= $dbConn->prepare("CALL `testSp`()");
$prepopReturnStmt->execute();
$mysqliresult	= $prepopReturnStmt->get_result();
var_dump($mysqliresult); // This will work, and print $num_rows as 0, but $field_count as 1. $type is incorrect (1 instead of 0)
$result			= $mysqliresult->fetch_assoc(); // This causes the crash
var_dump($result);

Expected result:
----------------
class mysqli_result#3 (5) {
  public $current_field =>
  int(0)
  public $field_count =>
  int(1)
  public $lengths =>
  NULL
  public $num_rows =>
  int(1)
  public $type =>
  int(0)
}
D:\WebServer\htdocs\testScript2.php:12:
array(1) {
  [1] =>
  int(1)
}

Actual result:
--------------
class mysqli_result#3 (5) {
  public $current_field =>
  int(0)
  public $field_count =>
  int(1)
  public $lengths =>
  NULL
  public $num_rows =>
  int(0)
  public $type =>
  int(1)
}

/* Backtrace from Debug Diagnostic Tool */
php7ts!mysqlnd_fetch_stmt_row_cursor+69 [c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\ext\mysqlnd\mysqlnd_ps.c @ 1044]   c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\ext\mysqlnd\mysqlnd_ps.c @ 1044 
php7ts!mysqlnd_mysqlnd_res_fetch_row_pub+2d [c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\ext\mysqlnd\mysqlnd_result.c @ 1245]   c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\ext\mysqlnd\mysqlnd_result.c @ 1245 
php7ts!mysqlnd_mysqlnd_res_fetch_into_pub+59 [c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\ext\mysqlnd\mysqlnd_result.c @ 1730 + 1f]   c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\ext\mysqlnd\mysqlnd_result.c @ 1730 + 1f 
php_mysqli!php_mysqli_fetch_into_hash+103 [c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\ext\mysqli\mysqli.c @ 1261]   c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\ext\mysqli\mysqli.c @ 1261 
php_xdebug_2_7_1_7_3_vc15_x86_64+6f3a    
php7ts!ZEND_DO_FCALL_SPEC_RETVAL_USED_HANDLER+19a [c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\zend\zend_vm_execute.h @ 1116 + 6]   c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\zend\zend_vm_execute.h @ 1116 + 6 
php7ts!execute_ex+5f [c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\zend\zend_vm_execute.h @ 55334 + f]   c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\zend\zend_vm_execute.h @ 55334 + f 
php_xdebug_2_7_1_7_3_vc15_x86_64+6760    
php7ts!zend_execute+1a8 [c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\zend\zend_vm_execute.h @ 60882]   c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\zend\zend_vm_execute.h @ 60882 
php7ts!zend_execute_scripts+b9 [c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\zend\zend.c @ 1569]   c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\zend\zend.c @ 1569 
php7ts!php_execute_script+261 [c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\main\main.c @ 2632]   c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\main\main.c @ 2632 
php!do_cli+aa0 [c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\sapi\cli\php_cli.c @ 998]   c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\sapi\cli\php_cli.c @ 998 
php!main+6f8 [c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\sapi\cli\php_cli.c @ 1389 + 5]   c:\php-snap-build\php73\vc15\x64\php-7.3.4-ts\sapi\cli\php_cli.c @ 1389 + 5 
php!__scrt_common_main_seh+10c [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl @ 288 + 22]   f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl @ 288 + 22 
kernel32!BaseThreadInitThunk+14    
ntdll!RtlUserThreadStart+21

Patches

Add a Patch

Pull Requests

Add a Pull Request

 
PHP Copyright © 2001-2019 The PHP Group
All rights reserved.
Last updated: Sun Sep 15 14:01:27 2019 UTC