Edit report at https://bugs.php.net/bug.php?id=55703&edit=1

 ID:                 55703
 Updated by:         larue...@php.net
 Reported by:        eran at zend dot com
 Summary:            PHP crash when calling mysqli_fetch_fields
 Status:             Duplicate
 Type:               Bug
 Package:            MySQLi related
 Operating System:   Linux Ubuntu 11.04
 PHP Version:        5.3.8
-Assigned To:        
+Assigned To:        laruence
 Block user comment: N
 Private report:     N

 New Comment:

in that case, then change it to always be "def" is okey, thanks :)


Previous Comments:
------------------------------------------------------------------------
[2011-09-16 19:41:02] eran at zend dot com

Agreed. Same crash as #55662

Can you apply the attached patch? The patch simply avoids accessing the 
uninitialized pointer and 
sets the value to "def" (which like I mentioned in my previous post, is always 
the correct value, 
see here: http://dev.mysql.com/doc/refman/5.0/en/c-api-data-structures.html)

------------------------------------------------------------------------
[2011-09-16 08:51:07] larue...@php.net

plz look at #55662. anyway seems not only "explain" statement cause this 
segfault

------------------------------------------------------------------------
[2011-09-15 15:12:16] eran at zend dot com

Description:
------------
Hi,

Running the attached test script causes a crash in mysqli extension (in every 
run).
The crash comes from mysqli_api.c, at around line 1058:

add_property_string(value, "catalog", (field->catalog ? field->catalog : ""), 
1);

The member field->catalog contains an address to an uninitialized pointer.
Debugging libmysqlclient (self compiled, v5.1.58) shows that 
libmysqlclient simply left this member uninitialized, thus pointing to an 
uninitialized memory.

To work around this bug, I modified my PHP sources locally so the "catalog" 
value is always set to "def" (which according to the documentation 
http://dev.mysql.com/doc/refman/5.0/en/c-api-data-structures.html is always 
true) 
(I also had a patch for libmysqlclient, but I am not sure where to send it...)

This crash is reproducible in CLI mode using the test script attached.
Attached is the patch to mysqli extension as well.



Test script:
---------------
<?php
$host  = '127.0.0.1';
$user  = 'user';
$pass  = 'password';
$db    = 'mydb';
$port  = 3306;
$link = mysqli_init();
if (mysqli_real_connect($link, $host, $user, $pass, $db, $port)) {
        $stmt = mysqli_stmt_init($link);
        if(mysqli_stmt_prepare($stmt, "show processlist")) {
                $res     = mysqli_stmt_execute($stmt);
                $res_set = mysqli_stmt_result_metadata($stmt);
                var_dump ( $res_set );
                var_dump(mysqli_fetch_fields( $res_set ));
        }
}




------------------------------------------------------------------------



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