From: Daniel Borkmann Date: Wed, 11 Nov 2015 22:25:40 +0000 (+0100) Subject: packet: do skb_probe_transport_header when we actually have data X-Git-Tag: v4.2.8~52 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f61bba5058b013442466f2d9fdc64b59dabe5cb1;p=thirdparty%2Fkernel%2Fstable.git packet: do skb_probe_transport_header when we actually have data [ Upstream commit efdfa2f7848f64517008136fb41f53c4a1faf93a ] In tpacket_fill_skb() commit c1aad275b029 ("packet: set transport header before doing xmit") and later on 40893fd0fd4e ("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: c1aad275b029 ("packet: set transport header before doing xmit") Reported-by: Eric Dumazet Signed-off-by: Daniel Borkmann Acked-by: Jason Wang Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 71cb085e16fd7..ff4586f911e16 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2249,8 +2249,6 @@ 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); @@ -2330,6 +2328,9 @@ 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; }