udp: fix a race in encap_rcv handling
udp_queue_rcv_skb() has a possible race in encap_rcv handling, since this pointer can be changed anytime. We should use ACCESS_ONCE() to close the race. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -1397,6 +1397,8 @@ int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
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nf_reset(skb);
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if (up->encap_type) {
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int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
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/*
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* This is an encapsulation socket so pass the skb to
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* the socket's udp_encap_rcv() hook. Otherwise, just
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@ -1409,11 +1411,11 @@ int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
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*/
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/* if we're overly short, let UDP handle it */
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if (skb->len > sizeof(struct udphdr) &&
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up->encap_rcv != NULL) {
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encap_rcv = ACCESS_ONCE(up->encap_rcv);
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if (skb->len > sizeof(struct udphdr) && encap_rcv != NULL) {
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int ret;
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ret = (*up->encap_rcv)(sk, skb);
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ret = encap_rcv(sk, skb);
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if (ret <= 0) {
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UDP_INC_STATS_BH(sock_net(sk),
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UDP_MIB_INDATAGRAMS,
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