On Mon, Nov 23, 2020 at 05:32:51PM -0800, Nick Desaulniers wrote:

On Sun, Nov 22, 2020 at 8:17 AM Kees Cook [off-list ref] wrote:

quoted

On Fri, Nov 20, 2020 at 11:51:42AM -0800, Jakub Kicinski wrote:

quoted

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_CQ@mail.gmail.com/ (local)

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

I still think this isn't right -- it's a case statement that runs off
the end without an explicit flow control determination. I think Clang is
right to warn for these, and GCC should also warn.

-- 
Kees Cook