Re: [PATCH v9 06/27] rust: add C helpers

Kees Cook
2022-08-17T20:34:33Z

On Wed, Aug 17, 2022 at 10:22:37PM +0200, Miguel Ojeda wrote:
> On Wed, Aug 17, 2022 at 9:44 PM Kees Cook <keescook@chromium.org> wrote:
> > Given the distaste for ever using BUG()[1], why does this helper exist?
>
> We use it exclusively for the Rust panic handler, which does not
> return (we use fallible operations as much as possible, of course, but
> we need to provide a panic handler nevertheless).

Gotcha -- it's for the implicit situations (e.g. -C overflow-checks=on),
nothing is expected to explicitly call the Rust panic handler?

> Killing the entire machine is definitely too aggressive for some
> setups/situations, so at some point last year we discussed potential
> alternatives (e.g. `make_task_dead()` or similar) with, if I recall
> correctly, Greg. Maybe we want to make it configurable too. We are
> open to suggestions!

I suffer the same problems trying to fix C and the old "can never fail"
interfaces. Mainly we've just been systematically replacing such APIs
with APIs that return error codes, allowing the error to bubble back up.
(Which I know is exactly what you've already done with the allocator,
etc. Yay!)

-Kees

--
Kees Cook