Re: [PATCH net-next v4 3/6] net: dsa: Introduce dsa tagger data operation.

[Andrew Lunn <andrew@lunn.ch>]

>  		switch (code) {
>  		case DSA_CODE_FRAME2REG:
> -			/* Remote management is not implemented yet,
> -			 * drop.
> -			 */
> +			tagger_data = ds->tagger_data;
> +			if (likely(tagger_data->decode_frame2reg))
> +				tagger_data->decode_frame2reg(dev, skb);
>  			return NULL;
>  		case DSA_CODE_ARP_MIRROR:
>  		case DSA_CODE_POLICY_MIRROR:
> @@ -323,6 +326,25 @@ static struct sk_buff *dsa_rcv_ll(struct sk_buff *skb, struct net_device *dev,
>  	return skb;
>  }
  
> +static void dsa_tag_disconnect(struct dsa_switch *ds)
> +{
> +	kfree(ds->tagger_data);
> +	ds->tagger_data = NULL;
> +}


Probably a question for Vladimir.

Is there a potential use after free here? Is it guaranteed that the
masters dev->dsa_ptr will be cleared before the disconnect function is
called?

Also, the receive function checks for tagger_data->decode_frame2reg,
but does not check for tagger_data != NULL.

This is just a straight copy of tag_qca, so if there are issues here,
they are probably not new issues.

     Andrew