Stardata TSR on Win3.x Client Causes SNABase Service to Loop

Last reviewed: April 17, 1997
Article ID: Q150569

The information in this article applies to:

Microsoft SNA Server for Windows NT, versions 2.0, 2.1, and 2.11 Service Pack 1

SYMPTOMS

SNABase service will reach approximately 100% CPU utilization in Performance Monitor and all SNA Server clients connected to this SNA Server will be disconnected.

CAUSE

A badly written application running on a Windows 3.x computer overwrites the memory address occupied by the SNA Server Win3.x client-server interface DLL files. If the bad application hits a particular code segment (owned by the SNA Server components), it will cause SNA Server Win3.x client-server interface to send a bogus service table update to the SNA Server with the bad application's data. This causes the SNABase service running on the SNA Server to reach approximately 100% CPU utilization.

NOTE: Service table updates will normally flow from an SNA Server Win3.x client only when the client is configured to support the registration of an APPC invokable TP.

WORKAROUND

A fix was made to SNA Server:

To cause verbose validity checking on any incoming service table update

(msgtype 07); only the expected service table updates will be processed.

   In addition, the following application event will be logged when SNA
   Server receives a bad service table update from a client:

      631 - Invalid message received across the LAN.

To ignore any incoming service table update.

To cause SNA Server to ignore all incoming service table updates, set the following parameter:

\hkey_local_machine

  \system
    \current_control_set
          \Services
            \SNABase\
              \parameters: IgnoreClientUpdates:REG_DWORD:1

If this parameter has any non-zero value, the SNABase will ignore all client updates.

It will also log event 709 when it receives one.

NOTE: If this parameter is set up to ignore all incoming service table updates, a SNA Server Windows NT client running SNA Admin will not be able to administer the domain. Therefore, it is recommended that you not set this for IgnoreClientUpdates unless it is determined that verbose validity checking is not preventing the problem.

STATUS

Microsoft has confirmed this to be a problem in Microsoft SNA Server versions 2.0, 2.10, 2.11, and 2.11.sp1. This problem was corrected in the latest Microsoft SNA Server 2.11 U.S. Service Pack. For information on obtaining the service pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K

Additional query words: prodsna
Keywords : kbbug2.00 kbbug2.10 kbbug2.11 kbnetwork sna3rdparty snatp snawin3x
Version : 2.0 2.1 2.11 2.11.sp1
Platform : WINDOWS

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Last reviewed: April 17, 1997
© 1998 Microsoft Corporation. All rights reserved. Terms of Use.