A request may return a null pointer to the IFontDisp interface when a program that uses the Windows XP SP2 version of the Atl.dll file requests access to the ambient font property (887569)


The information in this article applies to:

  • Microsoft Windows XP Professional Service Pack 2 (SP2)
  • Microsoft Windows XP Home Edition Service Pack 2 (SP2)

SYMPTOMS

You may experience the following problem when a program uses the Microsoft Windows XP Service Pack 2 (SP2) version of the Atl.dll file to host ActiveX controls. When a program that uses this version of the Atl.dll file requests access to the ambient font property that is in an Active Template Library (ATL) host container, the request may return a null pointer to the IFontDisp interface.

When the null pointer is returned, an access violation may occur because most ActiveX controls do not recognize a null pointer. The program may stop responding. Or, the ActiveX controls may not work correctly.

CAUSE

This problem occurs because of a regression in the version of the Atl.dll file that is included with Windows XP SP2.

The control makes a call to the IAxWinAmbientDispatch::get_Font method. This call then causes the ATL!ATL::CAxHostWindow::get_Font method to be called. The call to the ATL!ATL::CAxHostWindow::get_Font method returns an S_OK HRESULT result. However, a null pointer is returned to the IFontDisp interface. Programs typically assume that a valid pointer is returned if the interface returns an S_OK HRESULT result. However, the control does not recognize the null pointer that is returned to the IFontDisp interface. Therefore, you experience the problems that are described in the "Symptoms" section.

RESOLUTION

Hotfix information

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Windows XP service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question. The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

Date         Time   Version            Size    File name
---------------------------------------------------------
11-Jan-2005  23:25  3.5.2284.1         58,880  Atl.dll

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

MORE INFORMATION

For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

Modification Type:MinorLast Reviewed:6/1/2006
Keywords:kbQFE kbHotfixServer kbWinXPsp3fix kbfix kbbug KB887569 kbAudITPRO
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