Subject: Re: [PATCH net-next] macvlan: Replace strncpy() by strscpy()

From: Stephen Hemminger <[email-masked]>
Date: Mon, 27 May 2019 14:20:26 -0700

On Mon, 27 May 2019 13:38:55 -0500
"Gustavo A. R. Silva" <[email-masked]> wrote:

> The strncpy() function is being deprecated. Replace it by the safer
> strscpy() and fix the following Coverity warning:
> 
> "Calling strncpy with a maximum size argument of 16 bytes on destination
> array ifrr.ifr_ifrn.ifrn_name of size 16 bytes might leave the destination
> string unterminated."
> 
> Notice that, unlike strncpy(), strscpy() always null-terminates the
> destination string.
> 
> Addresses-Coverity-ID: 1445537 ("Buffer not null terminated")
> Signed-off-by: Gustavo A. R. Silva <[email-masked]>
> ---
>  drivers/net/macvlan.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
> index 61550122b563..0ccabde8e9c9 100644
> --- a/drivers/net/macvlan.c
> +++ b/drivers/net/macvlan.c
> @@ -831,7 +831,7 @@ static int macvlan_do_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
>  	struct ifreq ifrr;
>  	int err = -EOPNOTSUPP;
>  
> -	strncpy(ifrr.ifr_name, real_dev->name, IFNAMSIZ);
> +	strscpy(ifrr.ifr_name, real_dev->name, IFNAMSIZ);
>  	ifrr.ifr_ifru = ifr->ifr_ifru;
>  
>  	switch (cmd) {

Why not use strlcpy like all the other places IFNAMSIZ is copied?