Patch "tcp: reset sk_rx_dst in tcp_disconnect()" has been added to the 4.11-stable tree

This is a note to let you know that I've just added the patch titled

tcp: reset sk_rx_dst in tcp_disconnect()

to the 4.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
tcp-reset-sk_rx_dst-in-tcp_disconnect.patch
and it can be found in the queue-4.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: WANG Cong <[email protected]>
Date: Sat, 24 Jun 2017 23:50:30 -0700
Subject: tcp: reset sk_rx_dst in tcp_disconnect()

From: WANG Cong <[email protected]>

[ Upstream commit d747a7a51b00984127a88113cdbbc26f91e9d815 ]

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.

---
 net/ipv4/tcp.c |    2 ++
 1 file changed, 2 insertions(+)

@@ -2325,6 +2325,8 @@ int tcp_disconnect(struct sock *sk, int
 	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 */

Patches currently in stable-queue which might be from [email protected] are

queue-4.11/ipv6-avoid-unregistering-inet6_dev-for-loopback.patch queue-4.11/tcp-reset-sk_rx_dst-in-tcp_disconnect.patch queue-4.11/tap-convert-a-mutex-to-a-spinlock.patch