Re: [Valgrind-developers] debugging valgrind

[Tom H. <th...@cy...>]

In message <200...@ac...>
          Julian Seward <js...@ac...> wrote:

> > > and with NX-aware processores and kernels it will no longer work.
> >
> > I'm no expert on that stuff, but I believe that GCC just turns off the
> > no-exec functionality in such systems in these cases.  Nasty, huh?
> 
> If the NX functionality is turnable-offable from user-space, how can it
> have any value as a security enhancement mechanism?

It can't be turned on and off on the fly, but gcc and the linker
can co-operate to mark an ELF file as needing (or not needing) an
executable stack and the kernel will pay attention to that when
starting the program.

So if you have a program that has an executable stack then it is
protected, but other programs are.

Tom

-- 
Tom Hughes (th...@cy...)
Software Engineer, Cyberscience Corporation
http://www.cyberscience.com/