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dccp: fix freeing skb too early for IPV6_RECVPKTINFO

In the current DCCP implementation an skb for a DCCP_PKT_REQUEST packet
is forcibly freed via __kfree_skb in dccp_rcv_state_process if
dccp_v6_conn_request successfully returns.

However, if IPV6_RECVPKTINFO is set on a socket, the address of the skb
is saved to ireq->pktopts and the ref count for skb is incremented in
dccp_v6_conn_request, so skb is still in use. Nevertheless, it gets freed
in dccp_rcv_state_process.

Fix by calling consume_skb instead of doing goto discard and therefore
calling __kfree_skb.

Similar fixes for TCP:

fb7e239 [TCP]: skb is unexpectedly freed.
0aea76d tcp: SYN packets are now
simply consumed

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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xairy authored and davem330 committed Feb 16, 2017
1 parent 785f357 commit 5edabca9d4cff7f1f2b68f0bac55ef99d9798ba4
Showing with 2 additions and 1 deletion.
  1. +2 −1 net/dccp/input.c
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@@ -606,7 +606,8 @@ int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
if (inet_csk(sk)->icsk_af_ops->conn_request(sk,
skb) < 0)
return 1;
goto discard;
consume_skb(skb);
return 0;
}
if (dh->dccph_type == DCCP_PKT_RESET)
goto discard;

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