netdev - Re: [PATCH net-next] wifi: airo: use strscpy() to instead of strncpy()

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Date:   Tue, 17 Jan 2023 22:27:57 +0100
From:   Johannes Berg <johannes@...solutions.net>
To:     yang.yang29@....com.cn, kvalo@...nel.org
Cc:     davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, akpm@...ux-foundation.org,
        songmuchun@...edance.com, brauner@...nel.org,
        julia.lawall@...ia.fr, gustavoars@...nel.org, jason@...c4.com,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, xu.panda@....com.cn
Subject: Re: [PATCH net-next] wifi: airo: use strscpy() to instead of
 strncpy()

On Fri, 2022-12-23 at 10:52 +0800, yang.yang29@....com.cn wrote:
> From: Xu Panda <xu.panda@....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@....com.cn>
> Signed-off-by: Yang Yang <yang.yang29@....com>
> ---
>  drivers/net/wireless/cisco/airo.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/cisco/airo.c b/drivers/net/wireless/cisco/airo.c
> index 7c4cc5f5e1eb..600a64f671ce 100644
> --- a/drivers/net/wireless/cisco/airo.c
> +++ b/drivers/net/wireless/cisco/airo.c
> @@ -6067,8 +6067,7 @@ static int airo_get_nick(struct net_device *dev,
>  	struct airo_info *local = dev->ml_priv;
> 
>  	readConfigRid(local, 1);
> -	strncpy(extra, local->config.nodeName, 16);
> -	extra[16] = '\0';
> +	strscpy(extra, local->config.nodeName, 17);
>  	dwrq->length = strlen(extra);
> 

Again, why bother. But is this even correct/identical behaviour?
Wouldn't it potentially read 17 input bytes before forcing NUL-
termination?

johannes