linux-kernel - Re: [PATCH net-next v2] net/rds: use strscpy() to instead of strncpy()

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Message-ID: <20230112211707.2abb31ad@kernel.org>
Date:   Thu, 12 Jan 2023 21:17:07 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     <yang.yang29@....com.cn>
Cc:     <santosh.shilimkar@...cle.com>, <davem@...emloft.net>,
        <edumazet@...gle.com>, <pabeni@...hat.com>,
        <netdev@...r.kernel.org>, <linux-rdma@...r.kernel.org>,
        <rds-devel@....oracle.com>, <linux-kernel@...r.kernel.org>,
        <xu.panda@....com.cn>
Subject: Re: [PATCH net-next v2] net/rds: use strscpy() to instead of
 strncpy()

On Wed, 11 Jan 2023 14:25:48 +0800 (CST) 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.

What are the differences in behavior between strncpy() and strscpy()?

> diff --git a/net/rds/stats.c b/net/rds/stats.c
> index 9e87da43c004..7018c67418f5 100644
> --- a/net/rds/stats.c
> +++ b/net/rds/stats.c
> @@ -88,9 +88,7 @@ void rds_stats_info_copy(struct rds_info_iterator *iter,
>  	size_t i;
> 
>  	for (i = 0; i < nr; i++) {
> -		BUG_ON(strlen(names[i]) >= sizeof(ctr.name));
> -		strncpy(ctr.name, names[i], sizeof(ctr.name) - 1);
> -		ctr.name[sizeof(ctr.name) - 1] = '\0';
> +		BUG_ON(strscpy(ctr.name, names[i], sizeof(ctr.name)) < 0);
>  		ctr.value = values[i];
> 
>  		rds_info_copy(iter, &ctr, sizeof(ctr));