# [PATCH 4.3.2RC2] COM Property Put Memory Leak

- Thread: https://externals.io/message/1318
- Original archive: https://news-web.php.net/php.internals/1318
- Started by Michael Sisolak on 2003-05-06T15:52:22+00:00
- Messages: 1
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## #1318 — Michael Sisolak — 2003-05-06T15:52:22+00:00

URL: https://externals.io/message/1318#1318

Attached is a patch for a memory leak that occurs when setting a COM
property to a string value.  According to Microsoft, when passing
parameters to Invoke
(http://msdn.microsoft.com/library/en-us/automat/htm/chap5_3kz7.asp):

"The calling code is responsible for releasing all strings and objects
referred to by rgvarg[ ] [the parameters passed to the Invoke call] or
placed in *pVarResult. As with other parameters that are passed by
value, if the invoked member must maintain access to a string after
returning, you should copy the string."

An example of this can be seen in the following code from MSDN (second
code block of
http://msdn.microsoft.com/library/en-us/automat/htm/chap3_76p4.asp):

   hr = pdisp->Invoke(dispid, IID_NULL, LOCALE_USER_DEFAULT, wFlags,
        &dispparams, pvRet, pexcepinfo, pnArgErr);

cleanup:
    // Clean up any arguments that need it.
    if (dispparams.cArgs != 0)
    {
        VARIANTARG * pvarg = dispparams.rgvarg;
        UINT cArgs = dispparams.cArgs;
        while (cArgs--)
        {
            switch (pvarg->vt)
            {
            case VT_BSTR:
                VariantClear(pvarg);
                break;
            }
            ++pvarg;
        }
    }
    delete dispparams.rgvarg;

The 4.3.2RC2 version of do_COM_propput() in ext/COM/COM.c, however,
only efrees the parameter array without first checking if the property
was a string that needs to be freed by the caller.  The attached patch
checks for a VT_BSTR parameter and calls VariantClear() if approprate.

Without this patch the following HTML/PHP page will grow a 4.3.2RC2
(under IIS5/PHP4ISAPI) processes memory usage without bound:

<?php

$xml = new COM("MSXML.DOMDocument");
$element = $xml->createElement("test");
$element->text = str_repeat("this is a text string!", 1000);
$val_a = com_get($element, "text");
$element->Release();
$xml->Release();

echo "val_a = {$val_a}<br><br>";
?>

<script>
setTimeout("document.location.reload(true);", 100);
</script>

With this patch in place there are no memory leaks when this code is
left to run.

Michael Sisolak
msisolak@yahoo.com

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