Re: [PATCH] x86: Don't randomize stack unless current->personality permits it

[Frank van Maarseveen <frankvm@frankvm.com>]

On Wed, Jul 12, 2006 at 06:03:18PM +0200, Andi Kleen wrote:
> Al Boldi <a1426z@gawab.com> writes:
> 
> > Frank van Maarseveen wrote:
> > >
> > > Do not randomize stack location unless current->personality permits it.
[...]
> > 
> > It still blips on my system.
> > 
> > echo 0 > /proc/sys/kernel/randomize_va_space makes the blips go away.
> > 
> > ???
> 
> fs/binfmt_elf.c:randomize_stack_top would need the same check

Actually, randomize_stack_top() checks

	if (current->flags & PF_RANDOMIZE) {

and it's only called from load_elf_binary() right after this:

	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
		current->flags |= PF_RANDOMIZE;

Further on create_elf_tables() is called and that one calls arch_align_stack()
so maybe it is more appropriate to test (current->flags & PF_RANDOMIZE) in
arch_align_stack() instead of recomputing it.

-- 
Frank