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Re: Buffer overflow prevention
From: Mariusz Woloszyn <emsi () ipartners pl>
Date: Mon, 18 Aug 2003 20:01:51 +0200 (EEST)

On Mon, 18 Aug 2003 pageexec () freemail hu wrote:

Anyways, on an i386 you can do W^X somewhat.  Not as perfectly as you
can on cpus that have a per-page X bit...

You are wrong again, PaX provides perfect per-page non-executable pages
using segmentation (SEGMEXEC), there are no restrictions on the ordering
of data/code pages like in OpenBSD.

BTW: have anyone tried to talk wih Linus about implementing some PaX (or
even GR) functionality in official Kernels?
I know that the argument for not implementing Solar Designer's
nonexecutable stack patch in official kernel was that it is easily
bypassable, so what about PaX???

I hate seeing GOT and other segments rwx nowdays (while it's marked as r-x
it IS executable).

Mariusz Wołoszyn
Internet Security Specialist, GTS - Internet Partners

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