SYMPTOMS

You have a computer that is running Windows Vista, Windows 7, Windows Server 2008, or Windows Server 2008 R2. You install an application that uses a Windows Filtering Platform (WFP) callout driver. After the application is running for some time, a memory leak may occur in the nonpaged pool memory. In this situation, you may experience low performance on the computer.

Note WFP callout drivers are usually used in third-party antivirus and firewall programs.
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CAUSE

When the WFP callout driver blocks a packet that has multiple Net Buffer List (NBL) chains, the last NBL in the chain is not released by the WFP callout driver correctly. This causes a nonpaged pool memory leak.
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RESOLUTION

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: http://support.microsoft.com/contactus/?ws=support (http://support.microsoft.com/contactus/?ws=support) Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

To apply this hotfix, you must be running Windows Vista, Windows 7, Windows Server 2008, or Windows Server 2008 R2.

Registry information

To use the hotfix in this package, you do not have to make any changes to the registry.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.

File information

The global version of this hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.

For all supported x86-based versions of Windows Server 2008 and of Windows Vista

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For all supported x64-based versions of Windows Server 2008 and of Windows Vista

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For all supported IA-64-based versions of Windows Server 2008

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Windows 7 and Windows Server 2008 R2 file information notes

Important Windows 7 hotfixes and Windows Server 2008 R2 hotfixes are included in the same packages. However, hotfixes on the Hotfix Request page are listed under both operating systems. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 7/Windows Server 2008 R2" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.

• The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information for Windows Server 2008 R2 and for Windows 7" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are extremely important to maintaining the state of the updated component. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.

For all supported x86-based versions of Windows 7

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For all supported x64-based versions of Windows 7 and of Windows Server 2008 R2

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For all supported IA-64-based versions of Windows Server 2008 R2

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STATUS

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

For more information about NBL, visit the following Microsoft Developer Network (MSDN) Web site: http://msdn.microsoft.com/en-us/library/bb245891.aspx (http://msdn.microsoft.com/en-us/library/bb245891.aspx) For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base: 824684 (http://support.microsoft.com/kb/824684/ ) Description of the standard terminology that is used to describe Microsoft software updates
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Additional file information

Additional file information for Windows Vista, Windows 7, Windows Server 2008 and for Windows Server 2008 R2

Additional files for all supported x86-based versions of Windows Server 2008 and Windows Vista

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Additional files for all supported x64-based versions of Windows Server 2008 and Windows Vista

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Additional files for all supported IA64-based versions of Windows Server 2008

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Additional files for all supported x86-based versions of Windows 7

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Additional files for all supported x64-based versions of Windows 7 and of Windows Server 2008 R2

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Additional files for all supported IA-64-based versions of Windows Server 2008 R2

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APPLIES TO

• Windows 7 Enterprise
• Windows 7 Home Basic
• Windows 7 Home Premium
• Windows 7 Professional
• Windows 7 Ultimate
• Windows Server 2008 R2 Datacenter
• Windows Server 2008 R2 Enterprise
• Windows Server 2008 R2 Standard
• Windows Server 2008 Datacenter without Hyper-V
• Windows Server 2008 Enterprise without Hyper-V
• Windows Server 2008 for Itanium-Based Systems
• Windows Server 2008 Standard without Hyper-V
• Windows Server 2008 Datacenter
• Windows Server 2008 Enterprise
• Windows Server 2008 Standard
• Windows Vista Enterprise 64-bit Edition
• Windows Vista Home Basic 64-bit Edition
• Windows Vista Home Premium 64-bit Edition
• Windows Vista Ultimate 64-bit Edition
• Windows Vista Business
• Windows Vista Business 64-bit Edition
• Windows Vista Enterprise
• Windows Vista Home Basic
• Windows Vista Home Premium
• Windows Vista Ultimate

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Article ID:
979223

Last Review:
April 14, 2010 - Revision: 2.0