[PATCH 4.4 16/17] ping: implement proper locking

Greg Kroah-Hartman
2017-04-28T08:31:34Z

From: Eric Dumazet <edumazet@google.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@google.com>
Reported-by: Daniel Jiang <danieljiang0415@gmail.com>
Reported-by: Solar Designer <solar@openwall.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/ipv4/ping.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -154,17 +154,18 @@ void ping_hash(struct sock *sk)
void ping_unhash(struct sock *sk)
{
struct inet_sock *isk = inet_sk(sk);
+
pr_debug("ping_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);
}
EXPORT_SYMBOL_GPL(ping_unhash);