Commit d747a7a5 authored Jun 24, 2017 by WANG Cong Committed by David S. Miller Jun 25, 2017

tcp: reset sk_rx_dst in tcp_disconnect()



We have to reset the sk->sk_rx_dst when we disconnect a TCP
connection, because otherwise when we re-connect it this
dst reference is simply overridden in tcp_finish_connect().

This fixes a dst leak which leads to a loopback dev refcnt
leak. It is a long-standing bug, Kevin reported a very similar
(if not same) bug before. Thanks to Andrei for providing such
a reliable reproducer which greatly narrows down the problem.

Fixes: 41063e9d ("ipv4: Early TCP socket demux.")
Reported-by: Andrei Vagin <avagin@gmail.com>
Reported-by: Kevin Xu <kaiwen.xu@hulu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 85cb73ff

net/ipv4/tcp.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -2330,6 +2330,8 @@ int tcp_disconnect(struct sock *sk, int flags)
		tcp_init_send_head(sk);
		memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
		__sk_dst_reset(sk);
		dst_release(sk->sk_rx_dst);
		sk->sk_rx_dst = NULL;
		tcp_saved_syn_free(tp);

		/* Clean up fastopen related fields */

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