Re: Linux kernel proactive security hardening

[Kees Cook <kees () ubuntu com>]

On Mon, Nov 08, 2010 at 10:33:32PM +0300, Vasiliy Kulikov wrote:
> On Mon, Nov 08, 2010 at 08:48 +0300, Solar Designer wrote:
> > 2. We could turn all function-local non-static definitions of:
> >
> > struct x y;
> >
> > into:
> >
> > struct x y = {};
> >
> > We could do this by pre-processing the source files
>
> With coccinelle it is trivial:
>
> @@
> identifier T, x, f;
> @@
>
> f(...)
> {
>  ...
>  struct T x
> + = {}
>  ;
>  ...
> }
>
> However, I don't think that all linux maintainers would be happy with
> this.
>
> > or with a patch to
> > gcc (introduce a command-line option to assume empty initializers for
> > all on-stack structs).
>
> IMO much better solution - instead of many MB trivial patch have small
> gcc patch.

Yeah, I'd like to see this area of gcc improved. It seems like
-Wmissing-field-initializers doesn't always do the right thing either.

I'm glad to see that using "= { }" wipes the entire structure, though. I
was worried that it would leave holes for padding, etc.

-Kees

-- 
Kees Cook
Ubuntu Security Team