linux-kernel - Re: [PATCH] Tools: lib: string: Fix isspace() parameter to avoid undefined behavior

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Date:   Fri, 19 Mar 2021 15:28:56 -0300
From:   Arnaldo Carvalho de Melo <acme@...hat.com>
To:     hyunji-Hong <onlygod0807@...il.com>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Tools: lib: string: Fix isspace() parameter to avoid
 undefined behavior

Em Fri, Mar 19, 2021 at 09:14:15AM +0900, hyunji-Hong escreveu:
> isspace() could be vulnerable in terms of unpredictable results. So, the parameter of the isspace() should be cast with 'unsigned int'. We found out that information through these sites. (Microsoft, Stack Overflow)
> url: [https://docs.microsoft.com/en-us/cpp/code-quality/c6328?view=msvc-160]
> url: [https://stackoverflow.com/questions/122721]

tools/ and the kernel versions of isspace are implemented in
include/linux/ctype.h and tools/include/linux/ctype.h.

- Arnaldo
 
> Signed-off-by: SeungHoon Woo, Hyunji Hong, Kyeongseok Yang <hyunji_hong@...ea.ac.kr>
> ---
>  tools/lib/string.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/lib/string.c b/tools/lib/string.c
> index 8b6892f959ab..7d01be5cdcf8 100644
> --- a/tools/lib/string.c
> +++ b/tools/lib/string.c
> @@ -123,7 +123,7 @@ size_t __weak strlcpy(char *dest, const char *src, size_t size)
>   */
>  char *skip_spaces(const char *str)
>  {
> -	while (isspace(*str))
> +	while (isspace((unsigned char)*str))
>  		++str;
>  	return (char *)str;
>  }
> @@ -146,7 +146,7 @@ char *strim(char *s)
>  		return s;
>  
>  	end = s + size - 1;
> -	while (end >= s && isspace(*end))
> +	while (end >= s && isspace((unsigned char)*end))
>  		end--;
>  	*(end + 1) = '\0';
>  
> -- 
> 2.17.1