SNA Server Event 686 When Using MS-DOS Client with ODI Stack

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

SYMPTOMS

If you use the SNA Server MS-DOS Client using Novell's ODI IPX/SPX protocol stack and the SNA Server DOS router to communicate with an AS/400, then SNA Server will log the following event prior to creating an SNA Server Dump file and Dr. Watson log:

Event 686 SNA server Internal Buffer pool error.

   Reason = invalid owner id
   Mdule = snabase. exe
   Process = 132
   Pool = trustedelts
   details = current 9Eh expected 15EAh

Application exception occurred:

   App: snaservr.DBG (pid=150)
   When: 3/18/1996 @ 19:10:9.145
   Exception number: c0000005 (access violation)

   App: snabase.DBG (pid=132)
   When: 4/13/1996 @ 12:43:53.762
   Exception number: 80000003 (hardcoded breakpoint)

CAUSE

The trap in SNASERVR.EXE occurs when the SNA Server buffer pool becomes corrupted. In this case, the corruption occurs because the client is sending a 10-byte frame to the SNA Server when it was expecting a 47-byte frame. Because the incoming frame was smaller than expected, SNA Server fills it in with zeroes or EBCDIC spaces that cause the buffer pool to become corrupted. The trap in SNABASE.EXE results because of the preceding trap in SNASERVR.EXE.

RESOLUTION

The IPX/SPX transport now verifies that the incoming message length is valid. If the length is invalid, the message is ignored and an event 631 is logged. Microsoft has updated the <snaroot>\snanw.dll file on both the SNA Server and the client to correct this problem.

STATUS

Microsoft has confirmed this to be a problem in Microsoft SNA Server version 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