SNA Server Access Violation in s1pcrefm()

• Microsoft SNA Server, versions 2.11, 2.11 SP1, 2.11 SP2, 3.0, 3.0 SP1

SYMPTOMS

The SNA Server service (Snaservr.exe) fails unexpectedly with an access violation; the following appears in the event log:

   Event ID: 624
   Source:   SNA Server
   Description: Creating dump file C:\SNA\Traces\Snadump.log for
   Snaservr.exe

<Ntroot>\Drwtsn32.log will include the following failure information:

   Application exception occurred:
      Application: exe\snaservr.DBG <process ID>
      When: <date and time>
      Exception number: c0000005 (access violation)

   [data omitted]

   State Dump for Thread Id <thread>

   EAX=00000000  EBX=00000000  ECX=00cc6360  EDX=000c0001  ESI=000d0019
   EDI=00cc6360  EIP=003a5200  ESP=002bfec8  EBP=000000ff  EFL=00000297
   CS=001b  DS=0023  ES=0023  SS=0023  FS=0038  GS=0000

   function: s1pcrefm

   fault -> 0x003a5200  0fbf4806         movsx    ecx,word ptr [eax+06]

   Stack back trace:

   FramePtr  RetAddr   Param1   Param2   Param3   Function Name
   002bfed4  003b1323  00cc6360 00000019 0000000d SNASERVR!s1pcrefm+0x10
   002bff18  003b1087  00420002 00000004 0042f7d4 SNASERVR!s1puclos+0x293 

CAUSE

A 3270 emulator is failing to send element data in an OPEN PLU response to the SNA Server. SNA Server is not expecting such an invalid message, which leads to an access violation.

NOTE: This problem is a symptom of a 3270 emulator logic error. It was not determined which 3270 emulator causes this problem, because this was only observed once at one customer site.

STATUS

Microsoft has confirmed this to be a problem in SNA Server versions 2.11, 2.11 SP1, and 2.11 SP2. A supported fix is now available, but has not been fully regression-tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next Service Pack that contains this fix. Contact Microsoft Technical Support for more information.

Microsoft has confirmed this to be a problem in SNA Server versions 3.0, and 3.0 SP1. This problem was corrected in the latest SNA Server version 3.0 U.S. Service Pack. For information on obtaining this Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

S E R V P A C K

MORE INFORMATION

With the fix applied, if the SNA Server receives an invalid OPEN PLU response (containing no element data), the message is ignored and the following error is logged to the Windows NT application event log:

   Event ID: 9
   Source:  SNA Server
   Description: (1117) Internal Message Sequence Error

   EXPLANATION:
   Invalid or unexpected message received by the SNA Server (node) from
   another SNA Server component (for example, the emulator or link service)

   SUBCODE
   X'1117'   Received an invalid message from a 3270 emulator 

Additional query words:

Keywords : kbnetwork snaserverservice kbfix3.00.sp2
Version : WINDOWS:2.11,2.11 SP1,2.11 SP2,3.0,3.0 SP1
Platform : WINDOWS
Issue type : kbbug