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

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Date:   Thu, 5 Jan 2023 14:04:41 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     yang.yang29@....com.cn
Cc:     andersson@...nel.org, linux-remoteproc@...r.kernel.org,
        linux-kernel@...r.kernel.org, xu.panda@....com.cn
Subject: Re: [PATCH linux-next] rpmsg: use strscpy() to instead of strncpy()

On Fri, Dec 23, 2022 at 10:44:10AM +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/rpmsg/rpmsg_ns.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/rpmsg/rpmsg_ns.c b/drivers/rpmsg/rpmsg_ns.c
> index c70ad03ff2e9..c7b5b60aef4d 100644
> --- a/drivers/rpmsg/rpmsg_ns.c
> +++ b/drivers/rpmsg/rpmsg_ns.c
> @@ -48,9 +48,7 @@ static int rpmsg_ns_cb(struct rpmsg_device *rpdev, void *data, int len,
>  	}
> 
>  	/* don't trust the remote processor for null terminating the name */
> -	msg->name[RPMSG_NAME_SIZE - 1] = '\0';
> -

This is broken.

> -	strncpy(chinfo.name, msg->name, sizeof(chinfo.name));
> +	strscpy(chinfo.name, msg->name, sizeof(chinfo.name));

In this case there isn't a need to use strscpy() since we _know_ from the above
that msg->name is NULL terminated.

>  	chinfo.src = RPMSG_ADDR_ANY;
>  	chinfo.dst = rpmsg32_to_cpu(rpdev, msg->addr);
> 
> -- 
> 2.15.2