Microsoft KB Archive/184998

= RDR May Read Or Write from Wrong File If File Is Memory Mapped and Transport Error Occurs =

Article ID: 184998

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Server 4.0, Terminal Server Edition
 * Microsoft Windows NT Workstation 4.0 Developer Edition
 * Microsoft Windows NT Server 4.0 Standard Edition

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This article was previously published under Q184998





SYMPTOMS
An application may write data to or read data from the wrong file if a client has the file open and an error occurs causing the network connection to close.

NOTE: This problem can occur only if the file is a memory-mapped file.



CAUSE
When the connection is closed, the RDR does not check the status of a memory-mapped file.



RESOLUTION
To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

152734 How to Obtain the Latest Windows NT 4.0 Service Pack



STATUS
Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.



MORE INFORMATION
The Windows NT Rdr.sys logs on to the server using your user name/password and receives a UID number to reference the session in future requests. The same is true for files. When a file is opened, the server will return a FID to reference the file in future requests. The UID/FID pair is used to establish logon privileges and file permissions in RDR requests. These UIDs and FIDs get recycled each connection. On a new connection, the numbers assigned start at the beginning. The issue is that, when the connection is closed, the RDR is notified and will set a status in the file object so no further I/O can be done on the file. However, the status is not checked in the case of a memory-mapped file. This causes the RDR to use an old UID/FID pair. If the UID/FID pair were in use, the wrong file would be accessed.

Keywords: kbhotfixserver kbqfe kbbug kbfix kbqfe KB184998

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