Re: [kernel-hardening] Re: [PATCH] video: constify geode ops structures

Julia Lawall
2015-11-09T17:48:31Z

On Mon, 9 Nov 2015, Emese Revfy wrote:

> On Mon, 9 Nov 2015 14:50:47 +0000 (GMT)
> Julia Lawall <julia.lawall@lip6.fr> wrote:
> > > Actually, it looks like Emese Revfy is going to merge the GCC plugin
> > > constify stuff sooner rather than later so maybe adding all these consts
> > > isn't going to be needed.
> >
> > Is there any advantage of const over the plugin? The consts are easy to
> > add.
>
> Hi,
>
> I think it's a very good advantage that the plugin constifies automatically
> without regular maintenance (e.g., generate patches with coccinelle,
> send patches to the maintainers every new kernel version). ;)
> But if it doesn't convince you, I did constification by hand (with a coccinelle
> script) some years ago.
> There are too many types that can be const and it took too long to prepare and
> get the maintainers to accept the patches.
> And it never ends as there are always new types that can be const.

What happens if some structures cannot be made const because there is a
reassignment somewhere? Is there any feedback about the problem?

julia

>
> > Does the plugin help for structures that have non-function fields?
> Yes, it does. See __do_const here:
> http://www.openwall.com/lists/kernel-hardening/2015/11/06/11
> or more about the constify plugin:
> https://pax.grsecurity.net/docs/PaXTeam-H2HC13-PaX-gcc-plugins.pdf
>
> --
> Emese
>