From mboxrd@z Thu Jan 1 00:00:00 1970 From: Willem de Bruijn Subject: [PATCH net] packet: only test po->has_vnet_hdr once in packet_snd Date: Tue, 26 Sep 2017 12:20:17 -0400 Message-ID: <20170926162017.60750-1-willemdebruijn.kernel@gmail.com> Cc: davem@davemloft.net, Willem de Bruijn To: netdev@vger.kernel.org Return-path: Received: from mail-qt0-f195.google.com ([209.85.216.195]:32880 "EHLO mail-qt0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964791AbdIZQUU (ORCPT ); Tue, 26 Sep 2017 12:20:20 -0400 Received: by mail-qt0-f195.google.com with SMTP id b1so7359263qtc.0 for ; Tue, 26 Sep 2017 09:20:20 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: From: Willem de Bruijn Packet socket option po->has_vnet_hdr can be updated concurrently with other operations if no ring is attached. Do not test the option twice in packet_snd, as the value may change in between calls. A race on setsockopt disable may cause a packet > mtu to be sent without having GSO options set. Fixes: bfd5f4a3d605 ("packet: Add GSO/csum offload support.") Signed-off-by: Willem de Bruijn Reviewed-by: Eric Dumazet --- net/packet/af_packet.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index d288f52c53f7..1da0851f51f2 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2840,6 +2840,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len) struct virtio_net_hdr vnet_hdr = { 0 }; int offset = 0; struct packet_sock *po = pkt_sk(sk); + bool has_vnet_hdr = false; int hlen, tlen, linear; int extra_len = 0; @@ -2883,6 +2884,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len) err = packet_snd_vnet_parse(msg, &len, &vnet_hdr); if (err) goto out_unlock; + has_vnet_hdr = true; } if (unlikely(sock_flag(sk, SOCK_NOFCS))) { @@ -2941,7 +2943,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len) skb->priority = sk->sk_priority; skb->mark = sockc.mark; - if (po->has_vnet_hdr) { + if (has_vnet_hdr) { err = virtio_net_hdr_to_skb(skb, &vnet_hdr, vio_le()); if (err) goto out_free; -- 2.14.1.821.g8fa685d3b7-goog