linux-kernel - Re: [PATCH] lib/string_helpers: rework overflow-dependent code

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Message-ID: <CAFhGd8qz3YT=fC3XKkD1ydwijps=7hzhLhvVrNpzyNxfXM0XKg@mail.gmail.com>
Date: Mon, 12 Aug 2024 13:05:30 -0700
From: Justin Stitt <justinstitt@...gle.com>
To: Kees Cook <kees@...nel.org>
Cc: Andy Shevchenko <andy@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, 
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] lib/string_helpers: rework overflow-dependent code

On Mon, Aug 12, 2024 at 11:44 AM Kees Cook <kees@...nel.org> wrote:
>
> On Thu, 08 Aug 2024 14:43:56 -0700, Justin Stitt wrote:
> > When @size is 0, the desired behavior is to allow unlimited bytes to be
> > parsed. Currently, this relies on some intentional arithmetic overflow
> > where --size gives us SIZE_MAX when size is 0.
> >
> > Explicitly spell out the desired behavior without relying on intentional
> > overflow/underflow.
> >
> > [...]
>
> Since we can't have allocations larger than INT_MAX, SIZE_MAX is
> sufficiently large for this use-case, and the "off by one" introduce
> here isn't meaningful. I prefer the improved readability and lack of
> wrapping pre-decrement.

Great! Thanks.

>
> Applied to for-next/hardening, thanks!
>
> [1/1] lib/string_helpers: rework overflow-dependent code
>       https://git.kernel.org/kees/c/5d6b91b74ccd
>
> Take care,
>
> --
> Kees Cook
>