4.4-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
@@ -1717,7 +1717,7 @@ 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);
}
@@ -2656,6 +2656,7 @@ static int packet_snd(struct socket *soc
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 *soc
goto out_unlock;
}
+ has_vnet_hdr = true;
}
if (unlikely(sock_flag(sk, SOCK_NOFCS))) {
@@ -2802,7 +2804,7 @@ static int packet_snd(struct socket *soc
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);
