linux-kernel - Re: [PATCH] net/smc: replace strncpy with strscpy

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Message-ID: <20250618105039.GE1699@horms.kernel.org>
Date: Wed, 18 Jun 2025 11:50:39 +0100
From: Simon Horman <horms@...nel.org>
To: Pranav Tyagi <pranav.tyagi03@...il.com>
Cc: wenjia@...ux.ibm.com, jaka@...ux.ibm.com, davem@...emloft.net,
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
	linux-rdma@...r.kernel.org, linux-s390@...r.kernel.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	alibuda@...ux.alibaba.com, tonylu@...ux.alibaba.com,
	guwen@...ux.alibaba.com, skhan@...uxfoundation.org,
	linux-kernel-mentees@...ts.linux.dev
Subject: Re: [PATCH] net/smc: replace strncpy with strscpy

On Tue, Jun 17, 2025 at 05:55:12PM +0530, Pranav Tyagi wrote:
> Replace the deprecated strncpy() with strscpy() as the destination
> buffer should be NUL-terminated and does not require any trailing
> NUL-padding.
> 
> Signed-off-by: Pranav Tyagi <pranav.tyagi03@...il.com>
> ---
>  net/smc/smc_pnet.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/smc/smc_pnet.c b/net/smc/smc_pnet.c
> index b391c2ef463f..b70e1f3179c5 100644
> --- a/net/smc/smc_pnet.c
> +++ b/net/smc/smc_pnet.c
> @@ -370,7 +370,7 @@ static int smc_pnet_add_eth(struct smc_pnettable *pnettable, struct net *net,
>  		goto out_put;
>  	new_pe->type = SMC_PNET_ETH;
>  	memcpy(new_pe->pnet_name, pnet_name, SMC_MAX_PNETID_LEN);
> -	strncpy(new_pe->eth_name, eth_name, IFNAMSIZ);
> +	strscpy(new_pe->eth_name, eth_name, IFNAMSIZ);

Hi Pranav,

I think that because strscpy always results in a NULL terminated string
the length argument can be increased by one to IFNAMSIZ + 1, matching
the size of the destination.

But I also think that we can handle this automatically by switching
to the two-argument version of strscpy() because the destination is an
array.

	strscpy(new_pe->eth_name, eth_name);

>  	rc = -EEXIST;
>  	new_netdev = true;
>  	mutex_lock(&pnettable->lock);
> -- 
> 2.49.0
> 

-- 
pw-bot: changes-requested