FIX: An ISAPI extension that calls the WriteClient function 65,535 or more times sends an incomplete response in IIS 7.5

Applies to: Internet Information Services 7.5Windows Server 2008 R2 Service Pack 1

Symptoms


Consider the following scenario:
  • You install Internet Information Services (IIS) 7.5 and the Internet Server API (ISAPI) Extensions module on a computer that is running Windows 7 or Windows Server 2008 R2.
  • You create an ISAPI extension that calls the WriteClient function 65,535 or more times.
  • You enable the ISAPI extension to run on the computer.
  • A client request accesses a path that calls the ISAPI extension.

In this scenario, the WriteClient function call fails. Therefore, the client request is not processed correctly.

Cause


This problem occurs because an ERROR_ARITHMETIC_OVERFLOW error occurs when the WriteClient function is called 65,535 or more times.

Resolution


Hotfix information

A supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that is described in this article. Apply it only 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 software update that contains this hotfix.

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

Prerequisites

You must have the ISAPI Extensions module installed in IIS 7.5 to apply this hotfix. Additionally, the computer 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)

Restart information

You do not have to restart the computer after you apply this hotfix.

Replacement information

This hotfix does not replace a previously released hotfix.

File information

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 item in Control Panel.

Windows 7 and Windows Server 2008 R2 file information notes
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 are extremely important to maintain the state of the updated components.
For all supported x86-based versions of Windows 7
File nameFile versionFile sizeDateTimePlatform
Isapi.dll7.5.7600.21009106,49615-Jul-201107:19x86
Isapi.dll7.5.7601.21771106,49615-Jul-201105:42x86

For all supported x64-based versions of Windows 7 and of Windows Server 2008 R2
File nameFile versionFile sizeDateTimePlatform
Isapi.dll7.5.7600.21009120,32015-Jul-201107:21x64
Isapi.dll7.5.7601.21771120,32015-Jul-201105:17x64
Isapi.dll7.5.7600.21009106,49615-Jul-201107:19x86
Isapi.dll7.5.7601.21771106,49615-Jul-201105:42x86

For all supported IA-64-based versions of Windows Server 2008 R2
File nameFile versionFile sizeDateTimePlatform
Isapi.dll7.5.7600.21009244,73615-Jul-201107:13IA-64
Isapi.dll7.5.7601.21771244,73615-Jul-201104:06IA-64
Isapi.dll7.5.7600.21009106,49615-Jul-201107:19x86
Isapi.dll7.5.7601.21771106,49615-Jul-201105:42x86

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 WriteClient function, visit the following Microsoft Developer Network (MSDN) website:

Additional file information

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

Additional files for all supported x86-based versions of Windows 7
File nameUpdate.mum
File versionNot Applicable
File size2,868
Date (UTC)15-Jul-2011
Time (UTC)11:29
PlatformNot Applicable
File nameX86_1ba711089cfd23cd5b56abe95dd072d0_31bf3856ad364e35_6.1.7601.21771_none_9243a8fcd187592e.manifest
File versionNot Applicable
File size715
Date (UTC)15-Jul-2011
Time (UTC)11:29
PlatformNot Applicable
File nameX86_cfa1d95fc28689be127256a4a39638f8_31bf3856ad364e35_6.1.7600.21009_none_dd63dd8a79924841.manifest
File versionNot Applicable
File size715
Date (UTC)15-Jul-2011
Time (UTC)11:29
PlatformNot Applicable
File nameX86_microsoft-windows-i..iextensionsbinaries_31bf3856ad364e35_6.1.7600.21009_none_67a492aa659251cf.manifest
File versionNot Applicable
File size3,321
Date (UTC)15-Jul-2011
Time (UTC)08:00
PlatformNot Applicable
File nameX86_microsoft-windows-i..iextensionsbinaries_31bf3856ad364e35_6.1.7601.21771_none_693765ca62f88358.manifest
File versionNot Applicable
File size3,321
Date (UTC)15-Jul-2011
Time (UTC)06:13
PlatformNot Applicable

Additional files for all supported x64-based versions of Windows 7 and of Windows Server 2008 R2
File nameAmd64_6752b03ee4f9ce72ed95ff8ec068b471_31bf3856ad364e35_6.1.7600.21009_none_d38296dd8f46f929.manifest
File versionNot Applicable
File size1,080
Date (UTC)15-Jul-2011
Time (UTC)11:29
PlatformNot Applicable
File nameAmd64_cf7e70c30f75f084da07c35ae4be9d76_31bf3856ad364e35_6.1.7601.21771_none_491a43356b1003b8.manifest
File versionNot Applicable
File size1,080
Date (UTC)15-Jul-2011
Time (UTC)11:29
PlatformNot Applicable
File nameAmd64_microsoft-windows-i..iextensionsbinaries_31bf3856ad364e35_6.1.7600.21009_none_c3c32e2e1defc305.manifest
File versionNot Applicable
File size3,327
Date (UTC)15-Jul-2011
Time (UTC)08:49
PlatformNot Applicable
File nameAmd64_microsoft-windows-i..iextensionsbinaries_31bf3856ad364e35_6.1.7601.21771_none_c556014e1b55f48e.manifest
File versionNot Applicable
File size3,327
Date (UTC)15-Jul-2011
Time (UTC)07:00
PlatformNot Applicable
File nameUpdate.mum
File versionNot Applicable
File size3,306
Date (UTC)15-Jul-2011
Time (UTC)11:29
PlatformNot Applicable
File nameWow64_microsoft-windows-i..iextensionsbinaries_31bf3856ad364e35_6.1.7600.21009_none_ce17d88052508500.manifest
File versionNot Applicable
File size2,998
Date (UTC)15-Jul-2011
Time (UTC)07:43
PlatformNot Applicable
File nameWow64_microsoft-windows-i..iextensionsbinaries_31bf3856ad364e35_6.1.7601.21771_none_cfaaaba04fb6b689.manifest
File versionNot Applicable
File size2,998
Date (UTC)15-Jul-2011
Time (UTC)06:02
PlatformNot Applicable

Additional files for all supported IA-64-based versions of Windows Server 2008 R2
File nameIa64_03057c400e62e0ed18b2f9890a48a829_31bf3856ad364e35_6.1.7601.21771_none_94748f243d69b85b.manifest
File versionNot Applicable
File size1,078
Date (UTC)15-Jul-2011
Time (UTC)11:29
PlatformNot Applicable
File nameIa64_18d28e3ddfe11e0d46164e2fe9ef1c53_31bf3856ad364e35_6.1.7600.21009_none_8abd4e84a410bc1f.manifest
File versionNot Applicable
File size1,078
Date (UTC)15-Jul-2011
Time (UTC)11:29
PlatformNot Applicable
File nameIa64_microsoft-windows-i..iextensionsbinaries_31bf3856ad364e35_6.1.7600.21009_none_67a636a065905acb.manifest
File versionNot Applicable
File size3,324
Date (UTC)15-Jul-2011
Time (UTC)08:45
PlatformNot Applicable
File nameIa64_microsoft-windows-i..iextensionsbinaries_31bf3856ad364e35_6.1.7601.21771_none_693909c062f68c54.manifest
File versionNot Applicable
File size3,324
Date (UTC)15-Jul-2011
Time (UTC)07:25
PlatformNot Applicable
File nameUpdate.mum
File versionNot Applicable
File size2,347
Date (UTC)15-Jul-2011
Time (UTC)11:29
PlatformNot Applicable
File nameWow64_microsoft-windows-i..iextensionsbinaries_31bf3856ad364e35_6.1.7600.21009_none_ce17d88052508500.manifest
File versionNot Applicable
File size2,998
Date (UTC)15-Jul-2011
Time (UTC)07:43
PlatformNot Applicable
File nameWow64_microsoft-windows-i..iextensionsbinaries_31bf3856ad364e35_6.1.7601.21771_none_cfaaaba04fb6b689.manifest
File versionNot Applicable
File size2,998
Date (UTC)15-Jul-2011
Time (UTC)06:02
PlatformNot Applicable