Re: Potential static analysis ideas

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

On Sat, Jul 24, 2021 at 03:33:48PM +0200, Geert Uytterhoeven wrote:
> On Fri, Jul 23, 2021 at 9:11 PM Dan Carpenter 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?

https://lore.kernel.org/linux-media/YNMvarFl%2FKU1pGCG@pendragon.ideasonboard.com/

I think it would be useful, if not for the tools, at least for
developers.

-- 
Regards,

Laurent Pinchart