Microsoft KB Archive/169488

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Knowledge Base

Article ID: 169488

Article Last Modified on 6/30/2004


  • Microsoft SNA Server 3.0 Service Pack 4
  • Microsoft SNA Server 4.0

This article was previously published under Q169488


When you initially activate Windows NT Server Performance Monitor to collect SNA Server performance data, the following errors may occur:

  • Perfmon.exe may encounter an access violation.
  • If SNA Server is running on Windows NT Server 3.51, a Winlogon.exe access violation may occur, leading to a STOP 0x0000001E error.
  • If SNA Server is running on Windows NT Server 4.0, the following event may be logged in the Windows NT application event log:

          Event ID: 1013
          Source: Perflib
          The collect procedure in Extensible Counter DLL
          "C:\SNA\system\snaperf.dll" for the "SnaServr" service returned a
          buffer that was larger than the space allocated and may have
          corrupted the application's heap. This DLL should be disabled or
          removed from the system until the problem has been corrected to
          prevent further corruption. The application accessing this
          performance data should be restarted. The Performance data returned
          by counter DLL will be not be returned in Perf Data Block. Overflow
          size is data DWORD 0.
  • If SNA Server is running on Windows NT 4.0, a winlogon.exe access violation may occur, which would cause the following log entry in the <ntroot>\drwtsn32.log file:

          Application exception occurred:
          App: exe\winlogon.dbg (<process ID>)
          Exception number: c0000005 (access violation)
          function: RtlAllocateHeap
          FAULT ->77f64654 0fb716           movzx   edx,word ptr [esi]


The SNA Server performance monitoring collection routine returns a Buffer Size greater than the Perfmon buffer pointer allocated. The data collection routines AddNodeCounters and AddRTMCounters write data to the buffer, but fail to decrement the remaining byte count, which results in the buffer write operation going past the end of the buffer.


Microsoft has confirmed this to be a problem in SNA Server version 3.0 and 3.0 Service Pack 1. 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):



With the fix, the code has been modified to decrement the remaining byte count for the Node and RTM counter collections.

Additional query words: crash blue

Keywords: kbbug kbfix kbnetwork KB169488