Microsoft KB Archive/192298

= Third Party GINAs May Fail with Service Pack 4 Causing STOP 0x21A in WINLOGON =

Article ID: 192298

Article Last Modified on 2/27/2007

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APPLIES TO


 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Professional Edition
 * Microsoft Windows NT Workstation 4.0 Developer Edition
 * Microsoft Windows NT Server 4.0 Standard Edition
 * Microsoft Windows NT Server 4.0 Enterprise Edition
 * Microsoft Windows 2000 Advanced Server

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This article was previously published under Q192298



IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry



SYMPTOMS
In Windows NT 4.0 Service Pack 4, the interface version that WINLOGON asks for has been raised from 1.1 to 1.2. Because of this, third-party GINAs that do not do the version checking correctly might fail to initialize after you install Service Pack 4.

If the GINAs fail to initialize, Windows NT will stop with a stop 0xc000021A error because WINLOGON terminates because it needs a GINA module to function.

This change has an additional impact on so called stub GINAs. They need to properly forward the call to negotiate the interface version.



MORE INFORMATION
In Service Pack 4, there is a new Winlogon.exe that implements a new interface function and, because of this function, the interface version has been changed to 1.2. If a third-party GINA does not initialize with interface version 1.2, WINLOGON will fail because it cannot function without a GINA.

A stub GINA adds an additional layer of complexity because the third-party GINA needs to forward the interface version it supports to Msgina.dll and not the version WINLOGON has passed to it. Msgina.dll will initialize with interface version 1.1 and 1.2, but only supports 1.1. This behavior should guarantee that third-party GINAs with proper and half-way correct version checking continue to work with Service Pack 4.

Because of the nature of the change made for interface version 1.2, even stub GINAs with improper version checking (which do not filter out version 1.2) can work, but there is a good chance that they will break with future interface versions.

Samples for GINAs are in the Gina and Ginastub folders under Mssdk\Samples\WinBase\Security\WinNT in the Platform SDK.

The sample GINA does version checking correctly whereas GINASTUB does not filter out version 1.2. Stub GINAs based on this sample could possibly cause a problem.

This is a template for a proper WlxNegotiate implementation. It also includes code to remove the GINA from the registry in case initialization fails. This may not be appropriate for your stub GINA.

BOOL WINAPI WlxNegotiate(    DWORD       dwWinlogonVersion,     DWORD       *pdwDllVersion) {    BOOL bRetCode = TRUE;

if( !MyInitialize ) bRetCode = FALSE; else if (WLX_CURRENT_VERSION > dwWinlogonVersion) bRetCode = FALSE; // Don't allow old WINLOGON version, change as needed to support older versions else if (!GWlxNegotiate( WLX_CURRENT_VERSION, pdwDllVersion )             || WLX_CURRENT_VERSION != *pdwDllVersion) bRetCode = FALSE; // Don't allow mismatched MSGINAs, change as needed

*pdwDllVersion = WLX_CURRENT_VERSION;

if (!bRetCode) { HKEY hReg;

if (ERROR_SUCCESS != RegCreateKey (HKEY_LOCAL_MACHINE, "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Winlogon", &hReg)) return FALSE; if (ERROR_SUCCESS != RegDeleteValue (hReg, "GinaDll")) { RegCloseKey (hReg); // be a good citizen return FALSE; }        RegCloseKey (hReg);

MessageBox (NULL, "GINA initialization failed due to a version conflict. Please contact your manufacturer.\nThis GINA module was uninstalled.\nWindows NT will run into a stop screen when you press OK.", "Vendor GINA module", MB_OK); }

return bRetCode; }

Keywords: kbprb KB192298

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