[PATCH] ALSA: control-led: use strscpy in set_led_id()

[Jaroslav Kysela]

On 09. 01. 23 14:47, Jaroslav Kysela wrote:
> The use of strncpy() in the set_led_id() was incorrect.
> The len variable should use 'min(sizeof(buf2) - 1, count)'
> expression.
> 
> Use strscpy() function to simplify things and handle the error gracefully.
> 
> Reported-by: yang.yang29 at zte.com.cn
> BugLink: https://lore.kernel.org/alsa-devel/202301091945513559977@zte.com.cn/
> Cc: <stable at vger.kernel.org>
> Signed-off-by: Jaroslav Kysela <perex at perex.cz>
> ---
>   sound/core/control_led.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/sound/core/control_led.c b/sound/core/control_led.c
> index f975cc85772b..45c8eb5700c1 100644
> --- a/sound/core/control_led.c
> +++ b/sound/core/control_led.c
> @@ -530,12 +530,11 @@ static ssize_t set_led_id(struct snd_ctl_led_card *led_card, const char *buf, si
>   			  bool attach)
>   {
>   	char buf2[256], *s, *os;
> -	size_t len = max(sizeof(s) - 1, count);
>   	struct snd_ctl_elem_id id;
>   	int err;
>   
> -	strncpy(buf2, buf, len);
> -	buf2[len] = '\0';
> +	if (strscpy(buf2, buf, min(sizeof(buf2), count)) < 0)

Please, don't use this version of path (see v2). This min() expression will 
strip the last char and buf is '\0' terminated.

v2: https://lore.kernel.org/alsa-devel/20230109150119.342771-1-perex@perex.cz/

				Jaroslav

-- 
Jaroslav Kysela <perex at perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.