Path: utzoo!mnetor!uunet!husc6!think!ames!oliveb!sun!gorodish!guy
From: guy@gorodish.Sun.COM (Guy Harris)
Newsgroups: comp.unix.wizards
Subject: Re: Referencing through a null pointer
Message-ID: <51484@sun.uucp>
Date: 1 May 88 21:43:33 GMT
References: <4729@cup.portal.com> <1988Apr24.092740.8673@utzoo.uucp> <1013@unmvax.unm.edu>
Sender: news@sun.uucp
Lines: 17

> There is a problem; but there isn't an easy way to avoid it, short
> of deciding that a unix process should be loaded starting at address
> 1024 and make the first page non-readable.

Which is *precisely* what:

	1) John Bruner's modifications to 4BSD

and

	2) The "-z" flag in paging VAX S5R2.2

do.  You just need a way to tell the kernel about "page zero" versus "no page
zero" executables (so you don't have to recompile all your old binaries), which
COFF already has and which John Bruner added to 4BSD.

You may end up seeing this in some future 4BSD release.