Subject: Re: [PATCH RFC v2 net-next 12/28] p4tc: add header field create, get, delete, flush and dump

From: Simon Horman <[email-masked]>
Date: Mon, 5 Jun 2023 12:24:59 +0200

On Wed, May 17, 2023 at 07:02:16AM -0400, Jamal Hadi Salim wrote:

...

Hi Victor, Pedro and Jamal,

some minor feedback from my side.

> +static int _tcf_hdrfield_fill_nlmsg(struct sk_buff *skb,
> +				    struct p4tc_hdrfield *hdrfield)
> +{
> +	unsigned char *b = nlmsg_get_pos(skb);
> +	struct p4tc_hdrfield_ty hdr_arg;
> +	struct nlattr *nest;
> +	/* Parser instance id + header field id */
> +	u32 ids[2];
> +
> +	ids[0] = hdrfield->parser_inst_id;
> +	ids[1] = hdrfield->hdrfield_id;
> +
> +	if (nla_put(skb, P4TC_PATH, sizeof(ids), ids))
> +		goto out_nlmsg_trim;
> +
> +	nest = nla_nest_start(skb, P4TC_PARAMS);
> +	if (!nest)
> +		goto out_nlmsg_trim;
> +
> +	hdr_arg.datatype = hdrfield->datatype;
> +	hdr_arg.startbit = hdrfield->startbit;
> +	hdr_arg.endbit = hdrfield->endbit;

There may be padding at the end of hdr_arg,
which is passed uninitialised to nla_put below.

> +
> +	if (hdrfield->common.name[0]) {
> +		if (nla_put_string(skb, P4TC_HDRFIELD_NAME,
> +				   hdrfield->common.name))
> +			goto out_nlmsg_trim;
> +	}
> +
> +	if (nla_put(skb, P4TC_HDRFIELD_DATA, sizeof(hdr_arg), &hdr_arg))
> +		goto out_nlmsg_trim;
> +
> +	nla_nest_end(skb, nest);
> +
> +	return skb->len;
> +
> +out_nlmsg_trim:
> +	nlmsg_trim(skb, b);
> +	return -1;
> +}

...