From 1299f7e17e9e442be49a9b6011f6fe5259960ebb Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Tue, 26 Sep 2017 12:20:17 -0400 Subject: packet: only test po->has_vnet_hdr once in packet_snd [ Upstream commit da7c9561015e93d10fe6aab73e9288e0d09d65a6 ] 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 Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/packet/af_packet.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'net') diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index a018f437a8fd..241f69039a72 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1717,7 +1717,7 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags) } spin_unlock(&po->bind_lock); - if (err && !refcount_read(&match->sk_ref)) { + if (err && !atomic_read(&match->sk_ref)) { list_del(&match->list); kfree(match); } @@ -2656,6 +2656,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len) int vnet_hdr_len; struct packet_sock *po = pkt_sk(sk); unsigned short gso_type = 0; + bool has_vnet_hdr = false; int hlen, tlen, linear; int extra_len = 0; ssize_t n; @@ -2743,6 +2744,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len) goto out_unlock; } + has_vnet_hdr = true; } if (unlikely(sock_flag(sk, SOCK_NOFCS))) { @@ -2802,7 +2804,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len) packet_pick_tx_queue(dev, skb); - if (po->has_vnet_hdr) { + if (has_vnet_hdr) { if (vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) { u16 s = __virtio16_to_cpu(vio_le(), vnet_hdr.csum_start); u16 o = __virtio16_to_cpu(vio_le(), vnet_hdr.csum_offset); -- cgit v1.2.3