Re: [PATCH v3 1/2] kernel.h: Update comment about simple_strto() functions

Petr Mladek
2019-07-08T13:02:04Z

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@gmail.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.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