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packet: only test po->has_vnet_hdr once in packet_snd

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[ 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 <willemb@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Willem de Bruijn 2017-09-26 12:20:17 -04:00 committed by Greg Kroah-Hartman
parent 0f22167d33
commit 24ee394a82
1 changed files with 4 additions and 2 deletions
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6
net/packet/af_packet.c
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@ -1713,7 +1713,7 @@ 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);
}
@ -2838,6 +2838,7 @@ 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;
@ -2881,6 +2882,7 @@ 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)
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;