forked from luck/tmp_suning_uos_patched
udp: ipv4: must add synchronization in udp_sk_rx_dst_set()
Unlike TCP, UDP input path does not hold the socket lock.
Before messing with sk->sk_rx_dst, we must use a spinlock, otherwise
multiple cpus could leak a refcount.
This patch also takes care of renewing a stale dst entry.
(When the sk->sk_rx_dst would not be used by IP early demux)
Fixes: 421b3885bf
("udp: ipv4: Add udp early demux")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Shawn Bohrer <sbohrer@rgmadvisors.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
a1bf175087
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9750223102
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@ -1599,12 +1599,21 @@ static void flush_stack(struct sock **stack, unsigned int count,
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kfree_skb(skb1);
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}
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static void udp_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
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/* For TCP sockets, sk_rx_dst is protected by socket lock
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* For UDP, we use sk_dst_lock to guard against concurrent changes.
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*/
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static void udp_sk_rx_dst_set(struct sock *sk, struct dst_entry *dst)
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{
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struct dst_entry *dst = skb_dst(skb);
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struct dst_entry *old;
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dst_hold(dst);
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sk->sk_rx_dst = dst;
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spin_lock(&sk->sk_dst_lock);
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old = sk->sk_rx_dst;
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if (likely(old != dst)) {
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dst_hold(dst);
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sk->sk_rx_dst = dst;
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dst_release(old);
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}
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spin_unlock(&sk->sk_dst_lock);
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}
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/*
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@ -1737,10 +1746,11 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
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sk = skb_steal_sock(skb);
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if (sk) {
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struct dst_entry *dst = skb_dst(skb);
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int ret;
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if (unlikely(sk->sk_rx_dst == NULL))
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udp_sk_rx_dst_set(sk, skb);
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if (unlikely(sk->sk_rx_dst != dst))
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udp_sk_rx_dst_set(sk, dst);
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ret = udp_queue_rcv_skb(sk, skb);
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sock_put(sk);
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