0001-tcp-reset-sk_rx_dst-in-tcp_disconnect.patch

   1 From d747a7a51b00984127a88113cdbbc26f91e9d815 Mon Sep 17 00:00:00 2001
   2 From: WANG Cong <xiyou.wangcong@gmail.com>
   3 Date: Sat, 24 Jun 2017 23:50:30 -0700
   4 Subject: [PATCH] tcp: reset sk_rx_dst in tcp_disconnect()
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 We have to reset the sk->sk_rx_dst when we disconnect a TCP
  10 connection, because otherwise when we re-connect it this
  11 dst reference is simply overridden in tcp_finish_connect().
  12
  13 This fixes a dst leak which leads to a loopback dev refcnt
  14 leak. It is a long-standing bug, Kevin reported a very similar
  15 (if not same) bug before. Thanks to Andrei for providing such
  16 a reliable reproducer which greatly narrows down the problem.
  17
  18 Fixes: 41063e9dd119 ("ipv4: Early TCP socket demux.")
  19 Reported-by: Andrei Vagin <avagin@gmail.com>
  20 Reported-by: Kevin Xu <kaiwen.xu@hulu.com>
  21 Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
  22 Signed-off-by: David S. Miller <davem@davemloft.net>
  23 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  24 ---
  25  net/ipv4/tcp.c | 2 ++
  26  1 file changed, 2 insertions(+)
  27
  28 diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
  29 index b5ea036ca781..40aca7803cf2 100644
  30 --- a/net/ipv4/tcp.c
  31 +++ b/net/ipv4/tcp.c
  32 @@ -2330,6 +2330,8 @@ int tcp_disconnect(struct sock *sk, int flags)
  33         tcp_init_send_head(sk);
  34         memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
  35         __sk_dst_reset(sk);
  36 +       dst_release(sk->sk_rx_dst);
  37 +       sk->sk_rx_dst = NULL;
  38         tcp_saved_syn_free(tp);
  39
  40         /* Clean up fastopen related fields */
  41 --
  42 2.11.0
  43