Insecure hardware (was Re: gets(3) nonsense)

[Carl M. Fongheiser]

In article <1189 at cps3xx.UUCP> rang at 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
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