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List:       git-commits-head
Subject:    tcp: reset sk_rx_dst in tcp_disconnect()
From:       "Linux Kernel Mailing List" <linux-kernel () vger ! kernel ! org>
Date:       2017-06-29 21:34:35
Message-ID: 20170629213435.BC7CE22D7A () pdx-korg-gitolite-1 ! ci ! codeaurora ! org
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Web:        https://git.kernel.org/torvalds/c/d747a7a51b00984127a88113cdbbc26f91e9d815
Commit:     d747a7a51b00984127a88113cdbbc26f91e9d815
Parent:     85cb73ff9b74785a7fc752875d7f0fe17ca3ea7c
Refname:    refs/heads/master
Author:     WANG Cong <xiyou.wangcong@gmail.com>
AuthorDate: Sat Jun 24 23:50:30 2017 -0700
Committer:  David S. Miller <davem@davemloft.net>
CommitDate: Sun Jun 25 12:23:07 2017 -0400

    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: 41063e9dd119 ("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>
---
 net/ipv4/tcp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index b5ea036ca781..40aca7803cf2 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -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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