commit c16a3c626a7e04b099f341e4df3f2a0f1c869b9c
author David S. Miller <davem@davemloft.net> Fri May 01 22:02:47 2015 -0400
committer Thierry Strudel <tstrudel@google.com> Tue Jul 28 10:45:26 2015 -0700
tree adb02ac9701aa32c0ded489a3580b0056778b9cf
parent 8887dbc8268265461fa55dd03b118c865f9364e9

ipv4: Missing sk_nulls_node_init() in ping_unhash().

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>
Bug: 20770158
Change-Id: I944eb20fddea190892c2da681d934801d268096b

net/ipv4/ping.c

diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 8892913..9f89b0a 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -154,6 +154,7 @@
 	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 = 0;
 		isk->inet_sport = 0;