Re: [PATCH 5.14 018/334] nbd: add the check to prevent overflow in __nbd_ioctl()

Nick Desaulniers
2021-09-13T23:23:55Z

On Mon, Sep 13, 2021 at 4:00 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Mon, Sep 13, 2021 at 2:15 PM Nick Desaulniers
> <ndesaulniers@google.com> wrote:
> >
> > Sorry wrong diff:
>
> Well, this second diff was seriously whitespace-damaged and hard to
> read, but while it seems to be the same number of lines, it sure looks
> a lot more readable in this format.
>
> Except I think that
>
> default: dividend / divisor);
>
> should really have parentheses around both of those macro arguments.
>
> That's a preexisting problem, but it should be fixed while at it.

Ok, I'll send a revised v2 based on _Generic; Rasmus can help review
when he's awake.

> I'm also not sure why that (again, preexisting) BUILD_BUG_ON_MSG()
> only checks the size of the dividend, not the divisor. Very strange.
> But probably not worth worrying about.

I sent a not-yet-applied diff of my not-yet-applied diff. I was
playing with this last week, and IIRC we had divisors that were less
than 32b being promoted to int. But I'll test it some more.
--
Thanks,
~Nick Desaulniers