# \[PATCH\] ipv4: Missing sk\_nulls\_node\_init() in ping\_unhash().

- From: David Miller \<davem@davemloft.net\>
- Date: 2015-05-02 02:03:42 
- List: netdev
- Page: https://ratatoskr.run/netdev/2015/05/10985688

```text

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 <redacted>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/ipv4/ping.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index a93f260..05ff44b 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -158,6 +158,7 @@ void ping_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 = 0;
 		isk->inet_sport = 0;
-- 
2.1.0
```