Error in the client SMB protocol implementation in Windows

We have discovered an error in the client SMB protocol implementation in Windows together with Oracle engineers. The problem lies in accessing remote filesystem using SMB protocol. The problem is visible on Windows 8.1, but we have tested this with Windows 7 as well with the same result. The scenario leading to this problem is as follows:

1. Open a file on a remote filesystem that is accessed using SMB protocol.

2. Leave the file open for a long period of time without any activity - the file handle cannot be closed. The inactivity period has to be long enough for the SMB session to expire and TCP connection to the remote SMB server to be closed.

3. After some time perform some activity on the opened file, for example modify and save it.

4. The SMB session is reestablished, but Windows still uses the file ID from the previously closed SMB session in the new SMB session. This causes problems in accessing the file.

We have captured network traffic from such a session. This network traffic has been analysed by engineers in Oracle. We can provide the analysis that pinpoints the problem so that this bug can be eliminated in Windows.

July 13th, 2015 5:10am

Hi,

Please check the configuration and troubleshooting questions in this blog:

SMB 2.x and SMB 3.0 Timeouts in Windows
http://blogs.msdn.com/b/openspecification/archive/2013/03/27/smb-2-x-and-smb-3-0-timeouts-in-windows.aspx

Hope this could be helpful on your issue.

In addition, for questions on MS-SMB2, MS-SWN, MS-SMBD documents, please post in the Open Specifications Forum: Windows Protocols at http://social.msdn.microsoft.com/Forums/en-US/os_windowsprotocols.

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July 14th, 2015 10:49am

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