naim@nucsrl.UUCP (Naim Abdullah) (11/17/87)
I have run across a kernel device driver bug in System V, rel. 3.1
on ATT 3b2s. The bug is that opening /dev/ni for writing causes
a kernel panic. This is the documented way of sending data over 3BNET
and now that it causes a panic, I don't know what else to use for
sending packets over 3BNET. Note that this used to work fine in rel. 2.1.
I only discovered that it no longer worked, when we upgraded to rel. 3.1.
Here is a one liner that causes a panic (you can run this from any account).
main(){ return(open("/dev/ni", 1)); }
Running this gives:
TRAP
proc= 401CDCC0 psw= 280072B
pc= 4002AE74
PANIC: KERNEL MMU FAULT (F_ACCESS)
Please don't flame me for posting this program to cause the crash. If your
machine has this bug, I think you should know about this. Just turn off
write permissions on /dev/ni if you don't want Joe User to crash your
machine.
The strange thing is that nisend(1) continues to work fine. I wonder how
it sends data over 3BNET ?
Anyway, has anybody discovered any workarounds ? We have 5.3.1 sources so
bug fixes are welcome.
Naim Abdullah
Dept. of EECS,
Northwestern University
Internet: naim@eecs.nwu.edu
Uucp: {ihnp4, chinet, gargoyle}!nucsrl!naim
P.S: Notes cannot cross-post (yet), so I have posted copies of
this article in comp.unix.wizards, comp.unix.questions, comp.sys.att.
So you may see this article more than once.