[Samba] BSOD when writing from W2003 clients after SP2 has been installed

[Niko Neufeld]

Hi,

We are running a RHEL4 x86_64 server, samba-3.0.25b-1.el4_6.4. The server is
running with essentially the same configuration since a year without
problems. Due to a hardware failure on the back-end SAN the samba-server was
moved to a different machine (same OS, same samba version, same config). At
about the same time we deployed SP2 on various W2300 machines (there are in
total about 50 W2003 clients and about 20 WXP). Since then we observe the
following reproducible phenomenon:
Copying a file from the W2003 client to a samba share will cause the Windows
machine to crash, when the following conditions are met
1) SP2 is installed (this is the onlly necessary condition)
2) The file is sufficiently large (> 50 MB) (the larger file the more likely
the crash)
3) During or shortly after the copy, file properties are accessed (e.g. from
the Windows explorer)
4) Sometimes the file copy / property  access has to be retried a few times

The Windows crash-dumps hint to a corruption in netbd, but the crashes are
not uniform, sometimes there is no BSOD but the machine is frozen.

Removing SP2 solves the problem.

More observations:
* With loglevel 3 we observe nothing (to us) obviously problematic in the
samba logs (I can provide traces if this help)
* Spying on the traffic with wireshark on the server and the client did also
not reveal anything particularly unusual (but I freely admint that I have
very little knowlege about SMB!)
* It seems that the problem is timing related: forcing the interface in 10
Mbit/s (we run Gigabit everywhere) reduces the frequency of the crashes. It
is also less frequent on W2003 clients which are separated by more hops from
the server (you have to try 10 or 20 times on a server which has an average
latency (ping) of 0.5 ms while on a server with 0.1 ms it usually happens
after at most 3 trials).
* XP machines see no problem at all.
* I found only one vaguely related post on a German mailing-list, but maybe
I didn't google for the right key-words.

I did not (yet) try to upgrade to a later samba version, because I ran into
problems when compiling it (some conflict with some XFS headers) but I did
not spend much time on this yet. Would this be worth a try?

Any hint is very much appreciated.

Regards,

Niko