Symptoms

Consider the following scenario:

  • You run a third-party application on a computer that is running Windows 7 or Windows Server 2008 R2.

  • The application uses the Windows Filtering Platform (WFP) callout driver or the Network Driver Interface Specification (NDIS) Lightweight Filters (LWF) driver.

  • The application uses the FwpsNetBufferListAssociateContext0 function to associate the driver’s context and a Net Buffer List (NBL).

In this scenario, a memory leak occurs.

Cause

This issue occurs because the FwpsNetBufferListRemoveContext0 function does not free the context of a WFP callout driver or NDIS LWF driver that is associated with an NBL.

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 website:

http://support.microsoft.com/contactus/?ws=supportNote 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 one of the following operating systems:

  • Windows 7

  • Windows 7 Service Pack 1 (SP1)

  • Windows Server 2008 R2

  • Windows Server 2008 R2 Service Pack 1 (SP1)

For more information about how to obtain a Windows 7 or Windows Server 2008 R2 service pack, click the following article number to view the article in the Microsoft Knowledge Base:

976932 Information about Service Pack 1 for Windows 7 and for Windows Server 2008 R2

Registry information

To apply this hotfix, 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.

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.

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 files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:

    Version

    Product

    Milestone

    Service branch

    6.1.760
    0.17xxx

    Windows 7 and Windows Server 2008 R2

    RTM

    GDR

    6.1.760
    0.21xxx

    Windows 7 and Windows Server 2008 R2

    RTM

    LDR

    6.1.760
    1.18xxx

    Windows 7 and Windows Server 2008 R2

    SP1

    GDR

    6.1.760
    1.22xxx

    Windows 7 and Windows Server 2008 R2

    SP1

    LDR

  • GDR service branches contain only those fixes that are widely released to address widespread, critical issues. LDR service branches contain hotfixes in addition to widely released fixes.

  • 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 7 and for Windows Server 2008 R2" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are critical 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

File name

File version

File size

Date

Time

Platform

Netio.sys

6.1.7601.17939

240,496

22-Aug-2012

17:16

x86

Netio.sys

6.1.7601.22176

240,472

29-Nov-2012

05:41

x86

Fwpkclnt.sys

6.1.7600.17178

187,224

29-Nov-2012

05:08

x86

Tcpip.sys

6.1.7600.17178

1,287,512

29-Nov-2012

05:09

x86

Fwpkclnt.sys

6.1.7600.21385

187,224

29-Nov-2012

04:52

x86

Tcpip.sys

6.1.7600.21385

1,303,896

29-Nov-2012

04:52

x86

Fwpkclnt.sys

6.1.7601.18014

187,736

29-Nov-2012

05:11

x86

Tcpip.sys

6.1.7601.18014

1,293,672

29-Nov-2012

05:11

x86

Fwpkclnt.sys

6.1.7601.22176

187,736

29-Nov-2012

05:41

x86

Tcpip.sys

6.1.7601.22176

1,307,992

29-Nov-2012

05:41

x86

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

File name

File version

File size

Date

Time

Platform

Netio.sys

6.1.7601.17939

376,688

22-Aug-2012

18:12

x64

Netio.sys

6.1.7601.22176

376,680

29-Nov-2012

06:08

x64

Fwpkclnt.sys

6.1.7600.17178

287,576

29-Nov-2012

05:54

x64

Tcpip.sys

6.1.7600.17178

1,893,720

29-Nov-2012

05:54

x64

Fwpkclnt.sys

6.1.7600.21385

287,576

29-Nov-2012

05:43

x64

Tcpip.sys

6.1.7600.21385

1,877,352

29-Nov-2012

05:44

x64

Fwpkclnt.sys

6.1.7601.18014

288,088

29-Nov-2012

06:11

x64

Tcpip.sys

6.1.7601.18014

1,913,192

29-Nov-2012

06:11

x64

Fwpkclnt.sys

6.1.7601.22176

288,088

29-Nov-2012

06:08

x64

Tcpip.sys

6.1.7601.22176

1,901,928

29-Nov-2012

06:08

x64

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

File name

File version

File size

Date

Time

Platform

Netio.sys

6.1.7601.17939

711,024

22-Aug-2012

16:51

IA-64

Netio.sys

6.1.7601.22176

711,000

29-Nov-2012

04:55

IA-64

Fwpkclnt.sys

6.1.7600.17178

482,152

29-Nov-2012

04:57

IA-64

Tcpip.sys

6.1.7600.17178

3,789,656

29-Nov-2012

04:58

IA-64

Fwpkclnt.sys

6.1.7600.21385

482,136

29-Nov-2012

04:44

IA-64

Tcpip.sys

6.1.7600.21385

3,809,128

29-Nov-2012

04:44

IA-64

Fwpkclnt.sys

6.1.7601.18014

482,152

29-Nov-2012

04:54

IA-64

Tcpip.sys

6.1.7601.18014

3,796,824

29-Nov-2012

04:54

IA-64

Fwpkclnt.sys

6.1.7601.22176

482,136

29-Nov-2012

04:55

IA-64

Tcpip.sys

6.1.7601.22176

3,822,440

29-Nov-2012

04:55

IA-64


Status

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

More Information

For more information about the FwpsNetBufferListAssociateContext0 function, go to the following Microsoft website:

General information about FwpsNetBufferListAssociateContext0 functionFor more information about software update terminology, 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

Additional file information

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