At Usenix security symposium, one of the OpenBSD hacks (without a sense of
humour, I might add) presented a paper on buffer overflow protection by
hijacking register window changes.  The home page for the work done on this
can be found at:

http://stackghost.cerias.purdue.edu

Aside from Casper Dik telling the guy how register windows worked during
question time, it seems like a generally good idea.  Does one of the sparc
gurus here want to review for adoption in NetBSD ?  I'd have a go at it
but it is messing with stuff that I know others are better prepared to
deal with.

Darren