>> What I mean to say is that i386/machdep.c::sendsig() uses this logic to
>> send a signal to the precess when a bad stack is detected.

> not just a "bad stack", and *IMPOSSIBLE* stack.  read the code:

I think you allow weird stack segments (e.g., ss = 0; do you allow the
segment base to be nonzero?) so it's difficult to tell when a stack is
impossible - useracc() is inadequate.  Perhaps this could be handled like
copyout().

Bruce

------------------------------------------------------------------------------