Subject: Re: [PATCH net-next] net: virtio: use eth_hw_addr_set()

From: "Michael S. Tsirkin" <[email-masked]>
Date: Wed, 27 Oct 2021 03:23:17 -0400

On Tue, Oct 26, 2021 at 10:56:34AM -0700, Jakub Kicinski wrote:
> Commit 406f42fa0d3c ("net-next: When a bond have a massive amount
> of VLANs...") introduced a rbtree for faster Ethernet address look
> up. To maintain netdev->dev_addr in this tree we need to make all
> the writes to it go through appropriate helpers.
> 
> Signed-off-by: Jakub Kicinski <[email-masked]>

Acked-by: Michael S. Tsirkin <[email-masked]>

> ---
> CC: [email-masked]
> CC: [email-masked]
> CC: [email-masked]
> ---
>  drivers/net/virtio_net.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index c501b5974aee..b7f35aff8e82 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -3177,12 +3177,16 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	dev->max_mtu = MAX_MTU;
>  
>  	/* Configuration may specify what MAC to use.  Otherwise random. */
> -	if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC))
> +	if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC)) {
> +		u8 addr[MAX_ADDR_LEN];
> +
>  		virtio_cread_bytes(vdev,
>  				   offsetof(struct virtio_net_config, mac),
> -				   dev->dev_addr, dev->addr_len);
> -	else
> +				   addr, dev->addr_len);

Maybe BUG_ON(dev->addr_len > sizeof addr);

here just to make sure we don't overflow addr silently?

> +		dev_addr_set(dev, addr);
> +	} else {
>  		eth_hw_addr_random(dev);
> +	}
>  
>  	/* Set up our device-specific information */
>  	vi = netdev_priv(dev);
> -- 
> 2.31.1