netdev - Re: [PATCH net-next v2] rtnetlink: do_setlink: Use struct sockaddr

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Message-ID: <202505201431.B2E1B4F8EC@keescook>
Date: Tue, 20 May 2025 14:32:06 -0700
From: Kees Cook <kees@...nel.org>
To: Kuniyuki Iwashima <kuniyu@...zon.com>
Cc: Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>,
	Ido Schimmel <idosch@...dia.com>, netdev@...r.kernel.org,
	Stanislav Fomichev <sdf@...ichev.me>,
	Xiao Liang <shaw.leon@...il.com>, linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: Re: [PATCH net-next v2] rtnetlink: do_setlink: Use struct
 sockaddr_storage

On Tue, May 20, 2025 at 02:21:51PM -0700, Kees Cook wrote:
> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> index 6b7731739bbf..4953e202d0c0 100644
> --- a/net/core/rtnetlink.c
> +++ b/net/core/rtnetlink.c
> [...]
> @@ -3098,10 +3088,9 @@ static int do_setlink(const struct sk_buff *skb, struct net_device *dev,
>  		down_write(&dev_addr_sem);
>  		netdev_lock_ops(dev);
>  
> -		memcpy(sa->sa_data, nla_data(tb[IFLA_ADDRESS]),
> -		       dev->addr_len);
> -		err = netif_set_mac_address(dev, (struct sockaddr_storage *)sa, extack);
> -		kfree(sa);
> +		ss->sa_family = dev->type;
> +		memcpy(ss->__data, nla_data(tb[IFLA_ADDRESS]), dev->addr_len);
> +		err = netif_set_mac_address(dev, &ss, extack);
>  		if (err) {
>  			up_write(&dev_addr_sem);
>  			goto errout;

Ugh, sorry, this has a dependency on a separate patch. Please ignore
this; I will send them as a set.

-- 
Kees Cook