Re: Stack guards, PaX and such

[Arjan van de Ven <arjan@infradead.org>]

On Thu, 2004-12-30 at 10:12 +0100, David Jacoby wrote:
> Hi everyone!
> 
> I hope you had an nice and relaxing x-mas and are ready for a nice new 
> years eve.
> I just have a little question, i really dont if this has ben discussed 
> before, but if it
> has im really sorry.

are you talking about making the userspace stack not executable or the
kernel stacks?
With NX, userspace stacks already are not executable (and if you have a
cpu without NX you can use the execshield patches or PaX)

As for kernel stacks, well, with NX those are not executable either, and
to be honest, I can't remember the last time there was a user
exploitable kernel stack buffer overflow. So if your assertion is that
those are a common type of security problem, I disagree with you.
(One of the underlying causes is that the kernel stack is only really
small so it's relatively uncommon and deprecated to put arrays on the
kernel stack)