Re: [PATCH] mdadm: replace hard coded string length

[Jes Sorensen <Jes.Sorensen@redhat.com>]

Song Liu <songliubraving@fb.com> writes:
> This patch replaces hard coded 32 with sizeof(sb->set_name) in a
> couple places.
>
> Signed-off-by: Song Liu <songliubraving@fb.com>
> ---
>  super1.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/super1.c b/super1.c
> index 9f62d23..7d03b1f 100644
> --- a/super1.c
> +++ b/super1.c
> @@ -1030,7 +1030,7 @@ static void getinfo_super1(struct supertype *st, struct mdinfo *info, char *map)
>  
>  	memcpy(info->uuid, sb->set_uuid, 16);
>  
> -	strncpy(info->name, sb->set_name, 32);
> +	strncpy(info->name, sb->set_name, sizeof(sb->set_name));
>  	info->name[32] = 0;
>  
>  	if ((__le32_to_cpu(sb->feature_map)&MD_FEATURE_REPLACEMENT)) {
> @@ -1124,7 +1124,7 @@ static int update_super1(struct supertype *st, struct mdinfo *info,
>  		if (c)
>  			strncpy(info->name, c+1, 31 - (c-sb->set_name));
>  		else
> -			strncpy(info->name, sb->set_name, 32);
> +			strncpy(info->name, sb->set_name, sizeof(sb->set_name));
>  		info->name[32] = 0;
>  	}

I was about to apply this, but this is actually wrong. You need to use
the size of the destination, not of the source as the limit.

Sorry for the hassle.

Jes