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Subject: RE: [PATCH dpdk v2] net/tap: add software MAC address filtering
Date: Sat, 21 Mar 2026 06:48:38 +0100
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References: <20260319221034.703656-2-rjarry@redhat.com>
 <20260320164523.810401-2-rjarry@redhat.com>
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From: =?iso-8859-1?Q?Morten_Br=F8rup?= <mb@smartsharesystems.com>
To: "Stephen Hemminger" <stephen@networkplumber.org>,
 "Robin Jarry" <rjarry@redhat.com>
Cc: <dev@dpdk.org>
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> On Fri, 20 Mar 2026 17:45:24 +0100
> Robin Jarry <rjarry@redhat.com> wrote:
>=20
> > +	dst =3D rte_pktmbuf_mtod(mbuf, struct rte_ether_addr *);
> > +
> > +	if (likely(rte_is_unicast_ether_addr(dst))) {

The NULL addr check should go here:
    if (unlikely(rte_is_zero_ether_addr(dst)))
        return false; /* Invalid destination address in packet */

> > +		for (i =3D 0; i < TAP_MAX_MAC_ADDRS; i++) {
> > +			if (rte_is_same_ether_addr(dst, &data->mac_addrs[i]))
> > +				return true;
> > +		}
> > +		return false;
> > +	}
>=20
> Since unused slots are zero, probably need to drop packets with all
> zero dest.

You should drop packets with NULL dst addr; it is not allowed on the =
wire.

Alternatively, you can put the broadcast address in the unused entries =
in the mac_addrs table; it will not match any unicast ether addr.