On Sun, Nov 22, 2020 at 8:17 AM Kees Cook <[email protected]> wrote:
>
> On Fri, Nov 20, 2020 at 11:51:42AM -0800, Jakub Kicinski wrote:
> > If none of the 140 patches here fix a real bug, and there is no change
> > to machine code then it sounds to me like a W=2 kind of a warning.
>
> FWIW, this series has found at least one bug so far:
> https://lore.kernel.org/lkml/CAFCwf11izHF=g1mGry1fE5kvFFFrxzhPSM6qKAO8gxSp=kr...@mail.gmail.com/
So looks like the bulk of these are:
switch (x) {
case 0:
++x;
default:
break;
}
I have a patch that fixes those up for clang:
https://reviews.llvm.org/D91895
There's 3 other cases that don't quite match between GCC and Clang I
observe in the kernel:
switch (x) {
case 0:
++x;
default:
goto y;
}
y:;
switch (x) {
case 0:
++x;
default:
return;
}
switch (x) {
case 0:
++x;
default:
;
}
Based on your link, and Nathan's comment on my patch, maybe Clang
should continue to warn for the above (at least the `default: return;`
case) and GCC should change? While the last case looks harmless,
there were only 1 or 2 across the tree in my limited configuration
testing; I really think we should just add `break`s for those.
--
Thanks,
~Nick Desaulniers
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