Re: [PATCH linux-next] block: use strscpy() to instead of strncpy()

[Justin Stitt <justinstitt@google.com>]

On Sat, Dec 03, 2022 at 02:22:58PM +0800, yang.yang29@zte.com.cn wrote:
> From: Xu Panda <xu.panda@zte.com.cn>
>
> The implementation of strscpy() is more robust and safer.
> That's now the recommended way to copy NUL terminated strings.
>
> Signed-off-by: Xu Panda <xu.panda@zte.com.cn>
> Signed-off-by: Yang Yang <yang.yang29@zte.com>
Reviewed-by: Justin Stitt <justinstitt@google.com>
Cc: linux-hardening@vger.kernel.org

> ---
>  block/partitions/cmdline.c | 12 ++++--------
>  1 file changed, 4 insertions(+), 8 deletions(-)
>
> diff --git a/block/partitions/cmdline.c b/block/partitions/cmdline.c
> index 1af610f0ba8c..c03bc105e575 100644
> --- a/block/partitions/cmdline.c
> +++ b/block/partitions/cmdline.c
> @@ -81,8 +81,7 @@ static int parse_subpart(struct cmdline_subpart **subpart, char *partdef)
>
>  		length = min_t(int, next - partdef,
>  			       sizeof(new_subpart->name) - 1);
> -		strncpy(new_subpart->name, partdef, length);
> -		new_subpart->name[length] = '\0';
> +		strscpy(new_subpart->name, partdef, length);
>
>  		partdef = ++next;
>  	} else
> @@ -140,8 +139,7 @@ static int parse_parts(struct cmdline_parts **parts, const char *bdevdef)
>  	}
>
>  	length = min_t(int, next - bdevdef, sizeof(newparts->name) - 1);
> -	strncpy(newparts->name, bdevdef, length);
> -	newparts->name[length] = '\0';
> +	strscpy(newparts->name, bdevdef, length);
>  	newparts->nr_subparts = 0;
>
>  	next_subpart = &newparts->subpart;
> @@ -153,8 +151,7 @@ static int parse_parts(struct cmdline_parts **parts, const char *bdevdef)
>  		length = (!next) ? (sizeof(buf) - 1) :
>  			min_t(int, next - bdevdef, sizeof(buf) - 1);
>
> -		strncpy(buf, bdevdef, length);
> -		buf[length] = '\0';
> +		strscpy(buf, bdevdef, length);
>
>  		ret = parse_subpart(next_subpart, buf);
>  		if (ret)
> @@ -267,8 +264,7 @@ static int add_part(int slot, struct cmdline_subpart *subpart,
>
>  	label_min = min_t(int, sizeof(info->volname) - 1,
>  			  sizeof(subpart->name));
> -	strncpy(info->volname, subpart->name, label_min);
> -	info->volname[label_min] = '\0';
> +	strscpy(info->volname, subpart->name, label_min);
>
>  	snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
>  	strlcat(state->pp_buf, tmp, PAGE_SIZE);
> --
> 2.15.2