Microsoft KB Archive/169488

= Errors When Performance Monitoring SNA Server =

Article ID: 169488

Article Last Modified on 6/30/2004

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APPLIES TO


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

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This article was previously published under Q169488





SYMPTOMS
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 Description: 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 \drwtsn32.log file:      Application exception occurred: App: exe\winlogon.dbg () Exception number: c0000005 (access violation) [...]     function: RtlAllocateHeap [...]     FAULT ->77f64654 0fb716           movzx   edx,word ptr [esi] 

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CAUSE
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.

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STATUS
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):

S E R V P A C K

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MORE INFORMATION
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

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