Re: [PATCH nf-next 1/3] netfilter: nf_tables: add userdata support for nft_object

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Wed, Sep 02, 2020 at 11:12:39AM +0200, Jose M. Guisado Gomez wrote:
> diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
> index 6ccce2a2e715..55111aefd3db 100644
> --- a/net/netfilter/nf_tables_api.c
> +++ b/net/netfilter/nf_tables_api.c
[...]
> @@ -5954,32 +5957,48 @@ static int nf_tables_newobj(struct net *net, struct sock *nlsk,
>  	obj->key.name = nla_strdup(nla[NFTA_OBJ_NAME], GFP_KERNEL);
>  	if (!obj->key.name) {
>  		err = -ENOMEM;
> -		goto err2;
> +		goto err_strdup;
> +	}
> +
> +	if(nla[NFTA_OBJ_USERDATA]) {
> +		udlen = nla_len(nla[NFTA_OBJ_USERDATA]);
> +		obj->udata = kzalloc(udlen, GFP_KERNEL);
> +		if (obj->udata == NULL)
> +			goto err_userdata;
> +	} else {
> +		obj->udata = NULL;
> +	}
> +
> +	if (udlen) {
> +		nla_memcpy(obj->udata, nla[NFTA_OBJ_USERDATA], udlen);
> +		obj->udlen = udlen;
>  	}

Probably simplify this?

	if(nla[NFTA_OBJ_USERDATA]) {
		udlen = nla_len(nla[NFTA_OBJ_USERDATA]);
		obj->udata = kzalloc(udlen, GFP_KERNEL);
		if (obj->udata == NULL)
			goto err_userdata;

        	nla_memcpy(obj->udata, nla[NFTA_OBJ_USERDATA], udlen);
        	obj->udlen = udlen;
        }

obj is allocated via kzalloc(), so obj->udata is already guaranteed to
be initialized to NULL, no need for the 'else' side of the branch.

Thanks.