netdev - Re: [PATCH] caif: replace deprecated strncpy with strscpy

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Message-ID: <20240910093751.GA572255@kernel.org>
Date: Tue, 10 Sep 2024 10:37:51 +0100
From: Simon Horman <horms@...nel.org>
To: Justin Stitt <justinstitt@...gle.com>
Cc: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org, Kees Cook <kees@...nel.org>
Subject: Re: [PATCH] caif: replace deprecated strncpy with strscpy_pad

On Mon, Sep 09, 2024 at 04:39:28PM -0700, Justin Stitt wrote:
> strncpy() is deprecated for use on NUL-terminated destination strings [1] and
> as such we should prefer more robust and less ambiguous string interfaces.
> 
> Towards the goal of [2], replace strncpy() with an alternative that
> guarantees NUL-termination and NUL-padding for the destination buffer.

Hi Justin,

I am curious to know why the _pad variant was chosen.

> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://github.com/KSPP/linux/issues/90 [2]
> Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html
> Cc: Kees Cook <keescook@...omium.org>
> Cc: linux-hardening@...r.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@...gle.com>
> ---
> Note: build-tested only.
> ---
>  net/caif/chnl_net.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/caif/chnl_net.c b/net/caif/chnl_net.c
> index 47901bd4def1..ff37dceefa26 100644
> --- a/net/caif/chnl_net.c
> +++ b/net/caif/chnl_net.c
> @@ -347,7 +347,7 @@ static int chnl_net_init(struct net_device *dev)
>  	struct chnl_net *priv;
>  	ASSERT_RTNL();
>  	priv = netdev_priv(dev);
> -	strncpy(priv->name, dev->name, sizeof(priv->name));
> +	strscpy_pad(priv->name, dev->name);
>  	INIT_LIST_HEAD(&priv->list_field);
>  	return 0;
>  }
> 
> ---
> base-commit: bc83b4d1f08695e85e85d36f7b803da58010161d
> change-id: 20240909-strncpy-net-caif-chnl_net-c-a505e955e697
> 
> Best regards,
> --
> Justin Stitt <justinstitt@...gle.com>
> 
>