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Date:   Mon, 8 Jul 2019 15:01:59 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Geert Uytterhoeven <geert+renesas@...der.be>,
        Miguel Ojeda Sandonis <miguel.ojeda.sandonis@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mans Rullgard <mans@...sr.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/2] kernel.h: Update comment about
 simple_strto<foo>() functions

On Thu 2019-07-04 14:55:31, Andy Shevchenko wrote:
> There were discussions in the past about use cases for
> simple_strto<foo>() functions and, in some rare cases,
> they have a benefit over kstrto<foo>() ones.
> 
> Update a comment to reduce confusion about special use cases.
> 
> Suggested-by: Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
> - update comment based on Geert's input
>  include/linux/kernel.h | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> index 0c9bc231107f..63663c44933d 100644
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -332,8 +332,7 @@ int __must_check kstrtoll(const char *s, unsigned int base, long long *res);
>   * @res: Where to write the result of the conversion on success.
>   *
>   * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
> - * Used as a replacement for the obsolete simple_strtoull. Return code must
> - * be checked.
> + * Used as a replacement for the simple_strtoull. Return code must be checked.
>  */
>  static inline int __must_check kstrtoul(const char *s, unsigned int base, unsigned long *res)
>  {
> @@ -361,8 +360,7 @@ static inline int __must_check kstrtoul(const char *s, unsigned int base, unsign
>   * @res: Where to write the result of the conversion on success.
>   *
>   * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
> - * Used as a replacement for the obsolete simple_strtoull. Return code must
> - * be checked.
> + * Used as a replacement for the simple_strtoull. Return code must be checked.
>   */
>  static inline int __must_check kstrtol(const char *s, unsigned int base, long *res)
>  {
> @@ -438,7 +436,16 @@ static inline int __must_check kstrtos32_from_user(const char __user *s, size_t
>  	return kstrtoint_from_user(s, count, base, res);
>  }
>  
> -/* Obsolete, do not use.  Use kstrto<foo> instead */
> +/*
> + * Use kstrto<foo> instead.
> + *
> + * NOTE: The simple_strto<foo> does not check for overflow and,
> + *	 depending on the input, may give interesting results.

I am a bit confused whether the interesting results are caused
by the buffer overflow or if there is another reason.

If it is because of the overflow, I would remove the 2nd line. I guess
that anyone knows what a buffer overflow might cause.

Otherwise the patch looks fine to me.

Best Regards,
Petr

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