4.2, berknet and crashes

[lee at unmvax.UUCP]

 I have had some inquiries and TWO fixes. So, a followup:

The first fix, from Kirk Smith at Purdue (summmarized):
	Though We have not had any crashes we have seen some bizarre
	behavior on related (local) disciplines. The fix is to
	seperate the clist pointers from the mbuf pointers in tty.h.
	Just make them two structures instead of a union of two.

The second from Jim Madden at San Diego State:

One possible cause of this is that the distributed 4.2 Berknet driver,
bby_bk.c, includes code that attempts to disallow certain ioctl calls
once the bk line discipline has been invoked by looking at a "type"
code included in the definition of the ioctl values in sys/ioctl.h.
Unfortunately, the tty_bk.c test fails to properly isolate the type
code field from the rest of the word where it resides and will allow
some calls that it ought to prevent.  The most dangerous such call is
TIOCFLUSH which will deallocate various buffers while the driver is
using them and produce a system crash.  Here we experienced such
crashes when someone accidentally used the stty command against a
berknet line (eg. stty > /dev/linka).

A fix is attached.
				
				Jim Madden
				UCSD Network Services
				sdcsvax!madden


*** /tmp/,RCSt1004206	Wed Jan  2 16:18:18 1985
--- tty_bk.c	Mon Mar 12 16:40:22 1984
***************
*** 143,149
  	caddr_t data;
  {
  
! 	if ((cmd>>8) != 't')
  		return (-1);
  	switch (cmd) {
  

--- 143,149 -----
  	caddr_t data;
  {
  
! 	if (((cmd>>8)&0xff) != 't')
  		return (-1);
  	switch (cmd) {


 The one from Jim Madden was pretty much the same one that I was looking
for but could not find. We have no anamolous behavior at all. Just the crashes.
When I first started looking I was pretty sure that it was an ioctl and looked
at the same piece of code. Obviously, not carefully enough. This *looks*
like the cure for us but I have not tested it yet. Hope these help the
other people who mailed me. Thank you Kirk Smith and Jim Madden, very
much. If any more ideas come in I will accept them happily.

			Thanks for everybodies help and time,
				--Lee
-- 
			--Lee (Ward)
			{ucbvax,convex,gatech,pur-ee}!unmvax!lee