Re: kstrtojunk

[Kees Cook]

On Fri, Jul 1, 2016 at 5:53 AM, Alexey Dobriyan <adobriyan@xxxxxxxxx> wrote:
> Could you please stop converting to kstrtobool()?
>
> commit a81a5a17d44b26521fb1199f8ccf27f4af337a67
> Author: Kees Cook <keescook@xxxxxxxxxxxx>
> Date:   Thu Mar 17 14:22:57 2016 -0700
>
>     lib: add "on"/"off" support to kstrtobool
>
> Especially after doing patches like this?
>
> How on earth this was accepted?
>
> Now the kernel is supposed to know about every pair of words
> with the opposite meaning and accept them.
>
> If kstrtobool() is ever going to be added it should accept
> only '0' and '1' characters because kernel is not there
> to second guess (same logic applies to whitespace trimming
> for proc/sysfs files).
>
> Another point is that in C/C++ any value other than 0
> is true in for bool but kstrtobool() doesn't accept, say '2'
> as true. This is why it wasn't added in the first place.
>
> It is amazing to see how people think that every 2 common
> lines of code should be generalized and pushed into lib/.

There were plenty of common use-cases of the 0/1/no/yes/off/on usage.
I was specifically asked to use a common function, and this seemed
like the cleanest approach. kstrtobool already took y/n, and hasn't
ever handled "2" to mean "true", and is clearly documented. There's no
reason it couldn't be adjusted to do that, though.

-Kees

-- 
Kees Cook
Chrome OS & Brillo Security