Reproducable user mode system hang

[Charlie Brej <brejc8@vu.a.la>]

I have seem to have found a method to hang the kernel from user mode. The system 
hangs and does not print an Oops. It still responds to network pings but nothing 
else.

I have successfully crashed the 2.6 kernels on three different machines (all 
athlon 2.6 kernels):
Linux rain.cs.man.ac.uk 2.6.5-1.358 #1 Sat May 8 09:04:50 EDT 2004 i686 athlon 
i386 GNU/Linux
Linux solem.cs.man.ac.uk 2.6.6-1.374 #1 Wed May 19 12:44:14 EDT 2004 i686 athlon 
i386 GNU/Linux
Linux hogshead 2.4.20-8 #1 Thu Mar 13 17:18:24 EST 2003 i686 athlon i386 GNU/Linux

This problem does not occur on any 2.4 kernel machines I have tried.

Reproducing the problem:

Unfortunately the problem occurs in the middle of a program execution and I have 
been unable to track it down.

Download kmd 0.9.19pre1 from (If anyone wants I could distribute my binarys):
http://www.cs.man.ac.uk/~brejc8/kmd/dist/KMD-0.9.19.pre1.tar.gz
In user mode configure, compile and execute from the source directory:
"./kmd -e ./jimulator"
In the memory windows in the address box type in "E1000000" and press return.
This should now crash the system.

Kmd sporns an emulator (jimulator) with which it communicates using stdin/out 
pipes. I suspect it is a problem in the pipe communication. It occurs even when 
run under valgrind. I don't know of many methods of narrowing down the search.

-- 
         Charlie Brej
APT Group, Dept. Computer Science, University of Manchester
Web: http://www.cs.man.ac.uk/~brejc8/ Tel: +44 161 275 6844
Mail: IT302, Manchester University, Manchester, M13 9PL, UK