Re: [PATCH] x86/boot: Address clang -Wimplicit-fallthrough in vsprintf()

[Kees Cook]

On Thu, May 23, 2024 at 01:57:34PM +0200, Borislav Petkov wrote:
> On Fri, May 17, 2024 at 08:18:33AM -0700, Nathan Chancellor wrote:
> > There was a patch to make Clang match GCC's behavior a few years ago but
> > I think Kees made a good argument that GCC's behavior leaves potential
> > bugs on the table, so that was not pursued further.
> > 
> > https://reviews.llvm.org/D91895#2417170
> 
> Really? Maybe I'm being dense but I don't see real bugs there... I see
> readability issues. :-)

There isn't a bug _here_, but this is about making the code unambiguous
everywhere in the kernel. We've already done the work to get rid of
all these warnings; this one is newly introduced, so let's get it fixed.

We don't want to have the same flow-control statement reachable from two
different "case"s where the resulting behaviors are different. Otherwise
we can't determine if a "fallthrough" is missing or intentional.

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

-Kees

-- 
Kees Cook