SNA Server Access Violation May Occur If Link Fails to Start

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

SYMPTOMS

If an underlying link service fails to start, SNA Server may fail with an access violation (AV) immediately after it is started. When this happens, the following errors occur:

Windows NT application event log errors:

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

   Event ID: 4097
   Source:   DrWatson

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

   Application exception occurred:
      Application: exe\snaservr.DBG (pid=447)
      When: 1/23/1997 @ 14:56:5.593
      Exception number: c0000005 (access violation)

   [data omitted]

   State Dump for Thread Id 0x23b

   eax=00000000 ebx=004b1c00 ecx=00000000 edx=00000000 esi=00000001
   edi=00000001
   eip=003f60eb esp=00baff40 ebp=000700c8 iopl=0         nv up ei pl zr na
   po nc
   cs=001b  ss=0023  ds=0023  es=0023  fs=0038  gs=0000
   efl=00000246

   function: s1pulkiw
           003f60ce eb37             jmp     s1pulkiw+0x357 (003f6107)
           003f60d0 8b442414         mov     eax,[esp+0x14]
   ss:0262e947=???
           003f60d4 8b5004           mov     edx,[eax+0x4]
   ds:01a7ea06=???
           003f60d7 8bc1             mov     eax,ecx
           003f60d9 25ffff0000       and     eax,0xffff
           003f60de 8bc8             mov     ecx,eax
           003f60e0 c1e010           shl     eax,0x10
           003f60e3 03c1             add     eax,ecx
           003f60e5 c1c008           rol     eax,0x8
           003f60e8 0fbfc8           movsx   ecx,ax
   FAULT ->003f60eb 0fbf4204         movsx   eax,word ptr [edx+0x4]
   ds:01a7ea07

   *----> Stack Back Trace <----*

   FramePtr ReturnAd Param#1  Param#2  Param#3  Param#4  Function Name
   000700c8 00050001 00000000 00000000 0000007a 00020000 snaservr!s1pulkiw

CAUSE

If SNA Server receives a "lost locality" error from a link service before an Open(Link) response is received from the link service, SNA Server attempts to log the name of the failing connection by parsing the Open(Link) response. This leads to an access violation.

The cause of the link service "lost locality" may vary. In one case, the SNA 802.2/DLC link service failed to initialize because the token ring adapter cable was not inserted into the token ring network. This could have been due to any of the following reasons:

• The token ring cable was not inserted.
• The MAU port was inoperative.
• The adapter was configured for 16 Mbps and the token ring network was operating at a 4 Mbps ring speed.

RESOLUTION

To resolve this problem, obtain the hotfix mentioned below. However, the cause of the link service "lost locality" error must be debugged separately.

STATUS

Microsoft has confirmed this to be a problem in Microsoft SNA Server versions 2.0, 2.1, 2.11, and 2.11 Service Pack 1. A supported fix is now available for SNA Server 2.11 Service Pack 1, but is not 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.