4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Willem de Bruijn <will...@google.com>
[ 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 <will...@google.com>
Reviewed-by: Eric Dumazet <eduma...@google.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
net/packet/af_packet.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1713,7 +1713,7 @@ static int fanout_add(struct sock *sk, u
}
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);
}
@@ -2838,6 +2838,7 @@ static int packet_snd(struct socket *soc
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;
@@ -2881,6 +2882,7 @@ static int packet_snd(struct socket *soc
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 *soc
packet_pick_tx_queue(dev, skb);
- if (po->has_vnet_hdr) {
+ if (has_vnet_hdr) {
err = packet_snd_vnet_gso(skb, &vnet_hdr);
if (err)
goto out_free;
