Re: Potential static analysis ideas

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

Hi Dan,

On Fri, Jul 23, 2021 at 9:11 PM Dan Carpenter <dan.carpenter@oracle.com> wrote:
> These days we have disabled GCC's uninitialized warnings so it falls
> to static analysis devs to review all the new warnings.  I sometimes
> ignore warnings if they look like probably they aren't a bug.  Does this
> function allow zero size writes?  Does this switch statement really need
> a default case?  Maybe sometimes I miss bugs.

Yeah, I tended to find a few real bugs every release using the good old
gcc 4.2, before support for it was dropped.
I hope someone still runs modern compilers with GCC's uninitialized
warnings enabled again?

> Here is another example of something which I have a check for but I
> haven't pushed.
>
>         ret = frob();
>         if (!ret)
>                 return ret;
>
> This code is normally correct but sometimes it means the if statement is
> reversed and it should be "if (ret) return ret;".  To me returning a
> literal is always more clear but but clearly the original author felt
> "ret" was more clear...  It's only a few bugs per year so it's not a big
> deal either way.

To make it work well, you need to know if frob() and/or the current
function return an error code or not.  While you can use some heuristics
(e.g. is there any return -Exxx), perhaps we can add an annotation to
indicate if a function returns an error code, or an error pointer?

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