linux-kernel - Re: [PATCH] kstrtox: make kstrtobool_from

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Date:   Tue, 13 Feb 2018 19:18:08 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Alexey Dobriyan <adobriyan@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH] kstrtox: make kstrtobool_from_user() very strict

On Tue, Feb 13, 2018 at 7:11 PM, Alexey Dobriyan <adobriyan@...il.com> wrote:
> On Tue, Feb 13, 2018 at 06:02:27PM +0200, Andy Shevchenko wrote:
>> On Sat, Feb 10, 2018 at 11:11 PM, Alexey Dobriyan <adobriyan@...il.com> wrote:
>> > Once upon a time module parameter parsing code accepted
>> > 0, 1, y, n, Y and N for boolean values. Gratituous but contained
>> > to module code and thus tolerable.
>> >
>> > Commit ef951599074ba4fad2d0efa0a977129b41e6d203
>> > ("lib: move strtobool() to kstrtobool()") promoted that ugly wart
>> > to kstrtobool() and, more importantly, kstrtobool_from_user().
>> >
>> > Later set of accepted values was expanded to "on" and "of".
>> > Now there are 6+8=14(!) valid strings for a boolean.
>> >
>> > This patch reduces set of accepted values to "0" and "1"
>> > (with optional newline) in spirit with other kstrto*() functions.
>> >
>> > I'm starting with kstrtobool_from_user() as it is explicitly designed
>> > to be used for interacting with userspace. Currently there are 9 users
>> > all debug code, so there is hope.
>> >
>> > Please send before 4.16 so no real users start to depend on verbose behaviour.

>> NACK.
>> You basically are breaking ABI here. I don't see a zillion patches
>> which adds a tons of duplicate code to the corresponding users.
>
> Please do "find . -type f -name '*.[ch]' | xargs grep kstrtobool_from_user -w'
> before talking about zillion of patches.

If you wonder, I did it of course. The stylistic device I used here is
called "hyperbole".

Even for that dozen or so users I don't see how you handled the change.

-- 
With Best Regards,
Andy Shevchenko