Re: [PROPOSAL/PATCH] Remove PT_GNU_STACK support before 2.6.11

From: Ingo Molnar
Date: Sun Feb 06 2005 - 08:34:02 EST



* Andi Kleen <ak@xxxxxxx> wrote:

> On Sun, Feb 06, 2005 at 02:04:57PM +0100, Arjan van de Ven wrote:
> >
> > > Hmm, I got a report that it doesn't work anymore with
> > > 2.6.11rcs on x86-64. I haven't looked closely yet,
> > > but it wouldn't surprise me if this change isn't also involved.
> >
> > PT_GNU_STACK change is there since like 2.6.6 (and was put in by a suse person)
> > To me that is a strong indication that you are wrong on your
> > suspicion...
>
> Nah, the change to break 32bit userland mmap/mprotect like this was only
> put in after 2.6.10.

i suspect there may be some fundamental misunderstanding here. The
change to honor PT_GNU_STACK (on 64-bit) was added in April 2004 and
appeared in 2.6.6. The change to enforce the protection bits on x86 NX
CPUs (32-bit) was added in June 2004 and appeared in 2.6.8. I.e. it's
been part of the upstream kernel for more than half a year. Try it and
boot 2.6.8, you'll get NX protection. (I'm not sure about when it was
enabled for 32-bit emulation on the x64 kernel, you should be the one to
know that - but IIRC it was enabled prior 2.6.10.)

so i think you are on to the wrong victim :-)

Ingo
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