[SNAP]: Check packet length before reading
The snap_rcv code reads 5 bytes so we should make sure that we have 5 bytes in the head before proceeding. Based on diagnosis and fix by Evgeniy Polyakov, reported by Alan J. Wylie. Patch also kills the skb->sk assignment before kfree_skb since it's redundant. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -55,6 +55,9 @@ static int snap_rcv(struct sk_buff *skb, struct net_device *dev,
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.type = __constant_htons(ETH_P_SNAP),
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};
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if (unlikely(!pskb_may_pull(skb, 5)))
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goto drop;
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rcu_read_lock();
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proto = find_snap_client(skb_transport_header(skb));
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if (proto) {
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@ -62,14 +65,18 @@ static int snap_rcv(struct sk_buff *skb, struct net_device *dev,
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skb->transport_header += 5;
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skb_pull_rcsum(skb, 5);
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rc = proto->rcvfunc(skb, dev, &snap_packet_type, orig_dev);
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} else {
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skb->sk = NULL;
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kfree_skb(skb);
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rc = 1;
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}
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rcu_read_unlock();
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if (unlikely(!proto))
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goto drop;
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out:
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return rc;
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drop:
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kfree_skb(skb);
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goto out;
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}
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/*
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