Re: [PATCH RFC] gcc-plugins: Handle GCC version mismatch for OOT modules

Josh Poimboeuf
2021-01-26T23:02:01Z

On Tue, Jan 26, 2021 at 09:56:10AM -0800, Kees Cook wrote:
> On Mon, Jan 25, 2021 at 04:19:53PM -0600, Josh Poimboeuf wrote:
> > On Mon, Jan 25, 2021 at 02:03:07PM -0800, Kees Cook wrote:
> > > On Mon, Jan 25, 2021 at 02:42:10PM -0600, Josh Poimboeuf wrote:
> > > > When a GCC version mismatch is detected, print a warning and disable the
> > > > plugin. The only exception is the RANDSTRUCT plugin which needs all
> > > > code to see the same struct layouts. In that case print an error.
> > >
> > > I prefer this patch as-is: only randstruct needs a hard failure. The
> > > others likely work (in fact, randstruct likely works too).
> >
> > I'm curious about this last statement, why would randstruct likely work?
> >
> > Even struct module has '__randomize_layout', wouldn't basic module init
> > go splat?
>
> No; the seed is part of the generate includes -- you'll get the same
> layout with the same seed.

Right, but don't you need the plugin enabled to make use of that seed,
so the structs get interpreted properly by the module? Or am I
completely misunderstanding how this plugin works?

--
Josh