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