[cifs-protocol] Connection turn down problem in W2k8R2?

Volker Lendecke Volker.Lendecke at SerNet.DE
Thu Jan 5 09:21:37 MST 2012


Right now I'm trying to test and improve Samba's cleanup
routines. Testing those against W2k8R2 revealed that it
might have some slight problem here as well.

Not sure this is the right forum, but this is my most direct
channel :-)

I've added some code to Samba to artificially simulate a
crashing connection helper process, triggered by a magic
packet. In the attached trace, it is frame 43. It is a frame
with a normal NBSS header but instead of 0xFF"SMB" it has
the 4 letters "exit" as SMB header.

The attached trace tests brlock cleanup. Frame 16 creates a
file, frame 19 brlocks it. Frame 41 proves it's locked. Then
comes frame 43 which W2k8R2 properly responds to: It sends a
RST, because we sent garbage. I would have expected that the
brlock from frame 19 is cleaned up, but not so: Frame 46
proves it's still locked. Even more: MMC looking at the
local open files still shows that file open, although the
TCP connection does not exist anymore. So the only way to
access that file is to go to the server console and forcibly
close that file.

I'm sure this should NOT end up in the docs, I'd think this
is just a W2k8R2 server bug. If required, I'm happy to help
you reproduce this in your lab.

With best regards,

Volker Lendecke
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