linux-kernel - Re: [PATCH v2] Input: axp20x-pek - avoid needless newline removal

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Message-ID: <202309251100.A187272A49@keescook>
Date:   Mon, 25 Sep 2023 11:00:13 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Justin Stitt <justinstitt@...gle.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Chen-Yu Tsai <wens@...e.org>, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2] Input: axp20x-pek - avoid needless newline removal

On Mon, Sep 25, 2023 at 04:31:05AM +0000, Justin Stitt wrote:
> This code is doing more work than it needs to.
> 
> Before handing off `val_str` to `kstrtouint()` we are eagerly removing
> any trailing newline which requires copying `buf`, validating it's
> length and checking/replacing any potential newlines.
> 
> kstrtouint() handles this implicitly:
> kstrtouint ->
>   kstrotoull -> (documentation)
> |   /**
> |    * kstrtoull - convert a string to an unsigned long long
> |    * @s: The start of the string. The string must be null-terminated, and may also
> |    *  include a single newline before its terminating null. The first character
> |    ...
> 
> Let's remove the redundant functionality and let kstrtouint handle it.
> 
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@...r.kernel.org
> Suggested-by: Kees Cook <keescook@...omium.org>
> Signed-off-by: Justin Stitt <justinstitt@...gle.com>

This looks much cleaner. Thanks!

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook