From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann Subject: [PATCH net 1/2] packet: do skb_probe_transport_header when we actually have data Date: Fri, 6 Nov 2015 22:02:41 +0100 Message-ID: <5cdcd969eec9228a18c0dc54f9cc4b7b6b07ce05.1446842228.git.daniel@iogearbox.net> References: Cc: davem@davemloft.net, willemb@google.com, tklauser@distanz.ch, netdev@vger.kernel.org, Daniel Borkmann , Jason Wang To: edumazet@google.com Return-path: Received: from www62.your-server.de ([213.133.104.62]:55344 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965991AbbKFVCr (ORCPT ); Fri, 6 Nov 2015 16:02:47 -0500 In-Reply-To: In-Reply-To: References: Sender: netdev-owner@vger.kernel.org List-ID: 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 Cc: Jason Wang Signed-off-by: Daniel Borkmann --- net/packet/af_packet.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index af399ca..80c36c0 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -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; } -- 1.9.3