From d3df672020a93355bc8f683fc19694e0316381ab Mon Sep 17 00:00:00 2001
From: "David S. Miller" <davem@davemloft.net>
Date: Fri, 1 May 2015 22:02:47 -0400
Subject: [PATCH] ipv4: Missing sk_nulls_node_init() in ping_unhash().

commit a134f083e79fb4c3d0a925691e732c56911b4326 upstream.

If we don't do that, then the poison value is left in the ->pprev
backlink.

This can cause crashes if we do a disconnect, followed by a connect().

Tested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Wen Xu <hotdog3645@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 net/ipv4/ping.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index d495d4bcd745..6d622622e0df 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -139,6 +139,7 @@ static void ping_v4_unhash(struct sock *sk)
 	if (sk_hashed(sk)) {
 		write_lock_bh(&ping_table.lock);
 		hlist_nulls_del(&sk->sk_nulls_node);
+		sk_nulls_node_init(&sk->sk_nulls_node);
 		sock_put(sk);
 		isk->inet_num = isk->inet_sport = 0;
 		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
-- 
2.39.2