Question - non-exec stack

Question - non-exec stack

[Breno]

Hi,

I´d like to know  how non-exec stack can run on 32 bits processor. On 32bits
processor vm_exec and vm_read has the same flags . So your tasks will not
run very well.

att,
Breno Silva Pinto

Re: Question - non-exec stack

[Måns Rullgård]

"Breno" <brenosp@brasilsec.com.br> writes:

> I´d like to know  how non-exec stack can run on 32 bits processor. On 32bits
> processor vm_exec and vm_read has the same flags . So your tasks will not
> run very well.

This doesn't have anything to do with the CPU word size, does it?  I
guess you mean 32 bit Intel processors.

-- 
Måns Rullgård
mru@kth.se

Re: Question - non-exec stack

[Breno]

Yes , 32 bit Intel processors

Breno
----- Original Message -----
From: "Måns Rullgård" <mru@kth.se>
To: <linux-kernel@vger.kernel.org>
Sent: Friday, November 28, 2003 11:44 AM
Subject: Re: Question - non-exec stack


"Breno" <brenosp@brasilsec.com.br> writes:

> I´d like to know  how non-exec stack can run on 32 bits processor. On
32bits
> processor vm_exec and vm_read has the same flags . So your tasks will not
> run very well.

This doesn't have anything to do with the CPU word size, does it?  I
guess you mean 32 bit Intel processors.

--
Måns Rullgård
mru@kth.se

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Re: Question - non-exec stack

[William Lee Irwin III]

On Fri, Nov 28, 2003 at 11:57:09AM -0200, Breno wrote:
> Yes , 32 bit Intel processors

Due to the really hard drugs the processor designers must have been
on, the only way to implement this is via the particularly nasty flavor
of segmentation on Intel processors (sane forms just use bits in pointers).

c.f. pax and exec-shield for examples of how to do it in Linux (please
do not start that debate; the only relevant point here is they use the
segmentation stuff). I suspect OpenBSD might also implement it.


-- wli