Commit efdfa2f7 authored Nov 11, 2015 by Daniel Borkmann Committed by David S. Miller Nov 15, 2015

packet: do skb_probe_transport_header when we actually have data



In tpacket_fill_skb() commit c1aad275 ("packet: set transport
header before doing xmit") and later on 40893fd0 ("net: switch
to use skb_probe_transport_header()") was probing for a transport
header on the skb from a ring buffer slot, but at a time, where
the skb has _not even_ been filled with data yet. So that call into
the flow dissector is pretty useless. Lets do it after we've set
up the skb frags.

Fixes: c1aad275 ("packet: set transport header before doing xmit")
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent d7475de5

net/packet/af_packet.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -2368,8 +2368,6 @@ static int tpacket_fill_skb(struct packet_sock po, struct sk_buff skb,
		skb_reserve(skb, hlen);
		skb_reset_network_header(skb);

		if (!packet_use_direct_xmit(po))
		skb_probe_transport_header(skb, 0);
		if (unlikely(po->tp_tx_has_off)) {
		int off_min, off_max, off;
		off_min = po->tp_hdrlen - sizeof(struct sockaddr_ll);
		@@ -2449,6 +2447,9 @@ static int tpacket_fill_skb(struct packet_sock po, struct sk_buff skb,
		len = ((to_write > len_max) ? len_max : to_write);
		}

		if (!packet_use_direct_xmit(po))
		skb_probe_transport_header(skb, 0);

		return tp_len;
		}