Re: Potential static analysis ideas

[Geert Uytterhoeven <geert@linux-m68k.org>]

On Tue, Jul 27, 2021 at 11:38 AM Dan Carpenter <dan.carpenter@oracle.com> wrote:
> On Mon, Jul 26, 2021 at 08:50:39AM -0700, Paul E. McKenney wrote:
> > On Fri, Jul 23, 2021 at 10:10:23PM +0300, Dan Carpenter wrote:
> > > Rust has many good static analysis features but if we wanted we could
> > > implement a number of stricter rules in C.  With Smatch I have tried to
> > > focus on exclusively on finding bugs because everyone can agree that
> > > bugs are bad.  But if some subsystems wanted to implement stricter rules
> > > just as a hardenning measure then that's a doable thing.
> > >
> > > For example, I've tried a bunch of approaches to warning about when the
> > > user can trigger an integer overflow.  The challenge is that most
> > > integer overflows are harmless and do not cause a real life bug.
> >
> > I would not want overflow checks for unsigned integers, but it might
> > be helpful for signed integers.  But yes, most of us rely on fwrapv,
> > so that kernelwide checks for signed integer overflow will be quite noisy.
>
> Since we use -fwrapv then even signed integer overflows are defined and
> I haven't seen a way that checking for signed integer overflows can be
> useful.

For all people using git grep and investigating: we don't pass -fwrapv
explicitly, it is implied by -fno-strict-overflow.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds