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Commit 24ee394a authored by Willem de Bruijn's avatar Willem de Bruijn Committed by Greg Kroah-Hartman
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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: bfd5f4a3 ("packet: Add GSO/csum offload support.")
Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0f22167d

net/packet/af_packet.c

+4 −2
Original line number Diff line number Diff line
@@ -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;