linux-kernel - [PATCH 3.10 227/250] ping: implement proper locking

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Message-Id: <1496876436-32402-228-git-send-email-w@1wt.eu>
Date:   Thu,  8 Jun 2017 01:00:13 +0200
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Eric Dumazet <edumazet@...gle.com>,
        "David S . Miller" <davem@...emloft.net>, Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 227/250] ping: implement proper locking

From: Eric Dumazet <edumazet@...gle.com>

commit 43a6684519ab0a6c52024b5e25322476cabad893 upstream.

We got a report of yet another bug in ping

http://www.openwall.com/lists/oss-security/2017/03/24/6

->disconnect() is not called with socket lock held.

Fix this by acquiring ping rwlock earlier.

Thanks to Daniel, Alexander and Andrey for letting us know this problem.

Fixes: c319b4d76b9e ("net: ipv4: add IPPROTO_ICMP socket kind")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Reported-by: Daniel Jiang <danieljiang0415@...il.com>
Reported-by: Solar Designer <solar@...nwall.com>
Reported-by: Andrey Konovalov <andreyknvl@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
[wt: the function is ping_v4_unhash() in 3.10]
Signed-off-by: Willy Tarreau <w@....eu>
---
 net/ipv4/ping.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 431d597..0b778d7 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -135,17 +135,18 @@ static void ping_v4_hash(struct sock *sk)
 static void ping_v4_unhash(struct sock *sk)
 {
 	struct inet_sock *isk = inet_sk(sk);
+
 	pr_debug("ping_v4_unhash(isk=%p,isk->num=%u)\n", isk, isk->inet_num);
+	write_lock_bh(&ping_table.lock);
 	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;
 		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
-		write_unlock_bh(&ping_table.lock);
 	}
+	write_unlock_bh(&ping_table.lock);
 }
 
 static struct sock *ping_v4_lookup(struct net *net, __be32 saddr, __be32 daddr,
-- 
2.8.0.rc2.1.gbe9624a