Xref: utzoo comp.lang.c:14360 comp.unix.wizards:12967
Path: utzoo!utgpu!watmath!clyde!att!rutgers!rochester!pt.cs.cmu.edu!cadre!pitt!cisunx!cmf
From: cmf@cisunx.UUCP (Carl M. Fongheiser)
Newsgroups: comp.lang.c,comp.unix.wizards
Subject: Re: Insecure hardware (was Re: gets(3) nonsense)
Message-ID: <13974@cisunx.UUCP>
Date: 29 Nov 88 03:55:19 GMT
References: <867@cernvax.UUCP> <645@quintus.UUCP> <339@igor.Rational.COM> <4869@bsu-cs.UUCP> <14733@mimsy.UUCP> <1189@cps3xx.UUCP>
Reply-To: cmf@unix.cis.pittsburgh.edu (Carl M. Fongheiser)
Organization: Univ. of Pittsburgh, Comp & Info Sys
Lines: 18

In article <1189@cps3xx.UUCP> rang@cpswh.cps.msu.edu (Anton Rang) writes:
>  VAX processors do have separate bits for read, write, and execute on
>each page (I seem to vaguely recall one more).  The problem lies with
>the implementation of BSD and Ultrix, which leave the stack
>executable; I can't see any reason for this offhand.

Oh really?  Are you sure you're talking about a VAX? :-)

The only permissions that can be specified in a VAX PTE are read & write.
And they aren't really encoded in separate bits; instead, you have
values which specify the outermost mode which can write (and read) the
given page.  Note also, there's no such thing as a write-only page.
If you can write the page, you can also read it.

				Carl Fongheiser
				University of Pittsburgh
				...!pitt!cisunx!cmf
				cmf@unix.cis.pittsburgh.edu