SNA Server Access Violation in Function S1PWLUSE()

• Microsoft SNA Server, versions 2.11, 2.11 SP1, 2.11 SP2, 3.0, 3.0 SP1, 3.0 SP2, 3.0 SP3, 4.0, 4.0 SP1

SYMPTOMS

The SNA Server service may terminate unexpectedly causing all connected users to lose their existing host sessions. If Drwtsn32.exe is configured as the default debugger on the system, a Drwtsn32.log file similar to the following will be generated when this problem occurs:

Application exception occurred:
        App: exe\snaservr.DBG (pid=<process ID>)
        When: <data> @ <time>
        Exception number: c0000005 (access violation)

function: s1pwluse
        003ebb91 7514             jnz     s1pwluse+0xa7 (003ebba7)
        003ebb93 66c746180100     mov     word ptr [esi+0x18],0x1
ds:00f0ea07=????
        003ebb99 6a00             push    0x0
        003ebb9b e880060000       call    s1pwclps (003ec220)
        003ebba0 b101             mov     cl,0x1
        003ebba2 e9d9010000       jmp     s1pwluse+0x280 (003ebd80)
        003ebba7 663d1a00         cmp     ax,0x1a
        003ebbab 0f85cf010000     jne     s1pwluse+0x280 (003ebd80)
        003ebbb1 b101             mov     cl,0x1
        003ebbb3 e9c8010000       jmp     s1pwluse+0x280 (003ebd80)
FAULT ->003ebbb8 668b4618         mov     ax,[esi+0x18]
ds:00f0ea07=????
        003ebbbc 663d0100         cmp     ax,0x1
        003ebbc0 751a             jnz     s1pwluse+0xdc (003ebbdc)
        003ebbc2 66c746181500     mov     word ptr [esi+0x18],0x15
ds:00f0ea07=????
        003ebbc8 668b420c         mov     ax,[edx+0xc]
ds:021ea5c3=????
        003ebbcc 6689460e         mov     [esi+0xe],ax
ds:00f0ea07=????
        003ebbd0 e8eb040000       call    s1pwolpq (003ec0c0)
        003ebbd5 b101             mov     cl,0x1
        003ebbd7 e9a4010000       jmp     s1pwluse+0x280 (003ebd80)
        003ebbdc 663d1a00         cmp     ax,0x1a
        003ebbe0 0f859a010000     jne     s1pwluse+0x280 (003ebd80)
        003ebbe6 b101             mov     cl,0x1

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

FramePtr ReturnAd Param#1  Param#2  Param#3  Param#4  Function Name
000000ff 00000000 00000000 00000000 00000000 00000000 snaservr!s1pwluse
(FPO: [1,0,2])
000000ff 00000000 00000000 00000000 00000000 00000000 snaservr!<nosymbols> 

   Event ID: 624
   Source: SNA Server
   Description: Creating dump file <snaroot>\traces\snadump.log for
                snaservr.exe. 

CAUSE

The access violation in the S1PWLUSE() function is caused because the SNA Server service attempts to process an incorrectly formatted message that it received from a client across the native 3270 emulator interface (3270 Emulator Interface Specification).

RESOLUTION

Microsoft has confirmed this to be a problem in SNA Server versions 2.11, 2.11 SP1, 2.11 SP2, 3.0, 3.0 SP1, 3.0 SP2, 3.0 SP3, 4.0, and 4.0 SP1. We are researching this problem in SNA Server versions 2.11 and 3.0 and will post more information here in the Knowledge Base as it becomes available.

This problem was corrected in the latest SNA Server version 4.0 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

Additional query words:

Keywords :
Version : WINDOWS:2.11,2.11 SP1,2.11 SP2,3.0,3.0 SP1,3.0 SP2,3.0 SP3,4.0,4.0 SP1
Platform : WINDOWS
Issue type : kbbug