Fatal bug in NT 4.0 server (more comments)

[vytasvy () OSF LT (Vytautas Vysniauskas)]

Hi,

I would like to add more comments in relation with  my previous message.

System crash  was performed on NT 4.0 server and NT 4.0 worstation
platforms upgraded with the following patches:

Windows NT version 4.0, build 1381, Service Pack 2

   Q135707Q141239NTOSKRNLFIX was installed on Feb 23, 1997 at 16:41:21.
   Q163213 TCPIP DRIVER UPDATE was installed on Feb 23, 1997 at 16:41:47.
   Q163333SERIALFIX was installed on Mar 03, 1997 at 21:43:42.
   RPC SERVER CPU USAGE FIX was installed on Feb 23, 1997 at 16:41:33.


I think it is VERY ESSENTIAL that Linux client smbmount/smbumount
utility (from smbfs-2.0.1.tgz package) was compiled using 2.0.29 kernel
version but used with incompatible 2.0.25 kernel. I have tested that
smbmount/smbumount works just fine with Linux 2.0.29 client (installation
of smbfs-2.0.1 package patches smbfs kernel module, so it must be done
before 2.0.29 kernel is compiled). Compiled binaries (smbmount/smbumount)
are available at

ftp://puni.osf.lt/pub/windows/ntmount.tgz (~8Kb)
(md5sum is 3e053ae7d51954c96032aa91ead5364c )

Use it at your risk. It should work correctly with 2.0.29 (patched) kernel
version, but produces NT system crash when used with 2.0.25 Linux system.
Probably, something is wrong at filesystem level of NT system...

How this bug was discovered ?
----------------------------

Initially my goal was to integrate disk space resources of our NT server
and NFS server (Linux 2.0.25). At the first stage I have installed Samba
package (version 1.9.16p1) on the NFS server and configured Samba pasword
server to be NT server. In such a way Win 95/NT clients can access
transparently dedicated space of the NFS server.
The result was very encouraging:
Samba server (P5/100, 64Mb RAM, 3c579 EISA card, OS=Linux) performance over
10Mbits/sec LAN was  really better than NT server (P5/133x2, 64MB RAM, 3c595
PCI card).

I didn't make precise measurements, but copying of large files was up to
1.5 times faster when exchanging data with Samba server. From a client
point of view the difference was noticable in multimedia applications
(like playing remote MPEG files).

At the second stage my plan was to have disk space integration for
a UNIX client. I ftp'ed smbfs-2.0.1.tgz package. This package requires
Linux version 2.0.28 but our Linux servers & workstations were equipped
with 2.0.25 version. Before recompiling new kernel version ( it is
quite a long work to do) I have compiled this package using fresh source
code of the 2.0.29 kernel version (symbolic link /usr/src/linux was chaged
to the top of 2.0.29 souce directory). Then my thought  was to test
compiled smbmount/smbumount binaries on the older kernel version 2.0.25.
I expected my risk should  be to crash  Linux system rather NT server.
And ... I was really suprised that nothing wrong happened with Linux
box (only 'ls' process was hanging up) but NT server was crashing
immediatelly.  System crash was reproduced both on NT 4.0 server and
NT 4.0 workstation  platforms. When a disk mount was performed from
Linux 2.0.29 client (using the same compiled smbmount/smbumount binaries)
everything was working just fine.

========================================================
Vytautas Vysniauskas       e-mail: vytasvy () osf lt
                              tel: +370-2-611408
UNIX systems administrator
Open Society Fund of Lithuania,
========================================================