Re: [Minios-devel] [UNIKRAFT PATCH 1/3] lib/nolibc/string: fix underflow in strnlen

[Sharan Santhanam <sharan.santhanam@xxxxxxxxx>]

Hello Yuri,

This patch seems functionally fine. There is a checkpatch warning that 
can be fixed while upstreaming
Reviewed-by: Sharan Santhanam <sharan.santhanam@xxxxxxxxx>

Thanks & Regards
Sharan

On 12/4/18 6:16 PM, Yuri Volchkov wrote:
> The memchr return NULL if it did not find '\0' character. The strnlen
> did not take this into account and always did subtraction to count the
> string length.
>
> Return the provided length limit if the line ending is not found
> within this limit.
>
> Signed-off-by: Yuri Volchkov <yuri.volchkov@xxxxxxxxx>
> ---
>   lib/nolibc/string.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/lib/nolibc/string.c b/lib/nolibc/string.c
> index 6f853ba..fee2d10 100644
> --- a/lib/nolibc/string.c
> +++ b/lib/nolibc/string.c
> @@ -132,7 +132,8 @@ size_t strlen(const char *str)
>   
>   size_t strnlen(const char *str, size_t len)
>   {
> -       return (size_t)((uintptr_t)memchr(str, '\0', len) - (uintptr_t)str);
> +       const char *p = memchr(str, 0, len);
> +       return p ? (size_t) (p - str) : len;
>   }
>   
>   char *strncpy(char *dst, const char *src, size_t len)
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