Bug #51606 [NEW]: Memory Leak in odbc_result with long varchar columns

From: Date: Mon, 19 Apr 2010 19:56:02 +0000
Subject: Bug #51606 [NEW]: Memory Leak in odbc_result with long varchar columns
Groups: php.bugs 
Request: Send a blank email to php-bugs+get-149706@lists.php.net to get a copy of this message 
From:             
Operating system: Windows 2003
PHP version:      5.2.13
Package:          ODBC related
Bug Type:         Bug
Bug description:Memory Leak in odbc_result with long varchar columns

Description:
------------
When assigning the value returned from odbc_result to a variable and the
result value size is less than the current odbc_longreadlen size, the full
longreadlen memory amount is allocated instead of the smaller amount.

To fix this, if SQLGetData returns SQL_SUCCESS, we can use the length in
vallen to reallocate the memory for field to vallen, i.e. inserting the
lines 

} else if (rc == SQL_SUCCESS) {
	field = erealloc(field, result->values[field_ind].vallen);

after the rc == SQL_NO_DATA_FOUND check.  I've included a patch file, but
I'm not sure if I created that correctly.  I've recompiled with this patch
and the bug appears to be fixed.

Test script:
---------------
<?php
ini_set("memory_limit","1048576");
ini_set( "odbc.defaultlrl", "4096" );
$data = '0';
$db = odbc_connect('DSN', 'user', 'pass');
odbc_exec($db, 'CREATE TABLE Temp (contents long varchar)');
odbc_exec($db, 'INSERT INTO Temp (contents) VALUES (\'' . $data .
'\')');
$rst = odbc_exec($db, 'select * from Temp');
$contentArray = Array();
for($i = 0; $i < 1024; $i++){
	odbc_fetch_row($rst,1);
	$contentArray[] = odbc_result($rst, 'contents');
}
odbc_free_result($rst);
echo count($contentArray);
?>

Expected result:
----------------
1024

Actual result:
--------------
Fatal error: Allowed memory size of 1048576 bytes exhausted (tried to
allocate 4096 bytes) in D:\memLeakTest.php on line 12


-- 
Edit bug report at http://bugs.php.net/bug.php?id=51606&edit=1
-- 
Try a snapshot (PHP 5.2):            http://bugs.php.net/fix.php?id=51606&r=trysnapshot52
Try a snapshot (PHP 5.3):            http://bugs.php.net/fix.php?id=51606&r=trysnapshot53
Try a snapshot (PHP 6.0):            http://bugs.php.net/fix.php?id=51606&r=trysnapshot60
Fixed in SVN:                        http://bugs.php.net/fix.php?id=51606&r=fixed
Fixed in SVN and need be documented: http://bugs.php.net/fix.php?id=51606&r=needdocs
Fixed in release:                    http://bugs.php.net/fix.php?id=51606&r=alreadyfixed
Need backtrace:                      http://bugs.php.net/fix.php?id=51606&r=needtrace
Need Reproduce Script:               http://bugs.php.net/fix.php?id=51606&r=needscript
Try newer version:                   http://bugs.php.net/fix.php?id=51606&r=oldversion
Not developer issue:                 http://bugs.php.net/fix.php?id=51606&r=support
Expected behavior:                   http://bugs.php.net/fix.php?id=51606&r=notwrong
Not enough info:                     http://bugs.php.net/fix.php?id=51606&r=notenoughinfo
Submitted twice:                     http://bugs.php.net/fix.php?id=51606&r=submittedtwice
register_globals:                    http://bugs.php.net/fix.php?id=51606&r=globals
PHP 4 support discontinued:          http://bugs.php.net/fix.php?id=51606&r=php4
Daylight Savings:                    http://bugs.php.net/fix.php?id=51606&r=dst
IIS Stability:                       http://bugs.php.net/fix.php?id=51606&r=isapi
Install GNU Sed:                     http://bugs.php.net/fix.php?id=51606&r=gnused
Floating point limitations:          http://bugs.php.net/fix.php?id=51606&r=float
No Zend Extensions:                  http://bugs.php.net/fix.php?id=51606&r=nozend
MySQL Configuration Error:           http://bugs.php.net/fix.php?id=51606&r=mysqlcfg

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