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Commit be9164e7 authored by Kostya B's avatar Kostya B Committed by David S. Miller
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[IPv4] UFO: prevent generation of chained skb destined to UFO device 



Problem: ip_append_data() could wrongly generate a chained skb for
devices which support UFO.  When sk_write_queue is not empty
(e.g. MSG_MORE), __instead__ of appending data into the next nr_frag
of the queued skb, a new chained skb is created.

I would normally assume UFO device should get data in nr_frags and not
in frag_list.  Later the udp4_hwcsum_outgoing() resets csum to NONE
and skb_gso_segment() has oops.

Proposal:
1. Even length is less than mtu, employ ip_ufo_append_data()
and append data to the __existed__ skb in the sk_write_queue.

2. ip_ufo_append_data() is fixed due to a wrong manipulation of
peek-ing and later enqueue-ing of the same skb.  Now, enqueuing is
always performed, because on error the further
ip_flush_pending_frames() would release the queued skb.

Signed-off-by: default avatarKostya B <bkostya@hotmail.com>
Acked-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3a8209d1

net/ipv4/ip_output.c

+7 −15
Original line number Diff line number Diff line
@@ -753,23 +753,15 @@ static inline int ip_ufo_append_data(struct sock *sk, 
		skb->ip_summed = CHECKSUM_PARTIAL;

		skb->csum = 0;

		sk->sk_sndmsg_off = 0;

	}



	err = skb_append_datato_frags(sk,skb, getfrag, from,

			       (length - transhdrlen));

	if (!err) {

		/* specify the length of each IP datagram fragment */

		skb_shinfo(skb)->gso_size = mtu - fragheaderlen;

		skb_shinfo(skb)->gso_type = SKB_GSO_UDP;

		__skb_queue_tail(&sk->sk_write_queue, skb);



		return 0;

	}

	/* There is not enough support do UFO ,

	 * so follow normal path

	 */

	kfree_skb(skb);

	return err;



	return skb_append_datato_frags(sk, skb, getfrag, from,

				       (length - transhdrlen));

}



/*
@@ -863,9 +855,9 @@ int ip_append_data(struct sock *sk, 
		csummode = CHECKSUM_PARTIAL;



	inet->cork.length += length;

	if (((length > mtu) && (sk->sk_protocol == IPPROTO_UDP)) &&

	if (((length> mtu) || !skb_queue_empty(&sk->sk_write_queue)) &&

	    (sk->sk_protocol == IPPROTO_UDP) &&

	    (rt->u.dst.dev->features & NETIF_F_UFO)) {



		err = ip_ufo_append_data(sk, getfrag, from, length, hh_len,

					 fragheaderlen, transhdrlen, mtu,

					 flags);