[PATCH net] ping: implement proper locking

[PATCH net] ping: implement proper locking

[Eric Dumazet]

From: Eric Dumazet <edumazet@google.com>

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 Alexander and Andrey for letting us know of this problem.

Fixes: c319b4d76b9e ("net: ipv4: add IPPROTO_ICMP socket kind")
Reported-by: Solar Designer <solar@openwall.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
---
 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 2af6244b83e27ae384e96cf071c10c5a89674804..ccfbce13a6333a65dab64e4847dd510dfafb1b43 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -156,17 +156,18 @@ int 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);
 

Re: [PATCH net] ping: implement proper locking

[Solar Designer]

On Fri, Mar 24, 2017 at 04:29:45PM -0700, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
> 
> 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 Alexander and Andrey for letting us know of this problem.
> 
> Fixes: c319b4d76b9e ("net: ipv4: add IPPROTO_ICMP socket kind")
> Reported-by: Solar Designer <solar@openwall.com>
> Reported-by: Andrey Konovalov <andreyknvl@google.com>

We should credit the original reporter, who most likely found this by
fuzzing.  It's danieljiang0415 on GitHub and Twitter.  Unfortunately, I
don't know their e-mail address.  I'll try asking.

Alexander

Re: [PATCH net] ping: implement proper locking

[Xose Vazquez Perez]

Solar Designer wrote:

> We should credit the original reporter, who most likely found this by
> fuzzing.  It's danieljiang0415 on GitHub and Twitter.  Unfortunately, I
> don't know their e-mail address.  I'll try asking.

Daniel Jiang <danieljiang0415@gmail.com>

Re: [PATCH net] ping: implement proper locking

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 24 Mar 2017 16:29:45 -0700

> From: Eric Dumazet <edumazet@google.com>
> 
> 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 Alexander and Andrey for letting us know of this problem.
> 
> Fixes: c319b4d76b9e ("net: ipv4: add IPPROTO_ICMP socket kind")
> Reported-by: Solar Designer <solar@openwall.com>
> Reported-by: Andrey Konovalov <andreyknvl@google.com>

Eric, please add a proper signoff for yourself, and also please
add the following tag:

Reported-by: Daniel Jiang <danieljiang0415@gmail.com>

Thank you.

Re: [PATCH net] ping: implement proper locking

[Eric Dumazet]

On Fri, Mar 24, 2017 at 7:10 PM, David Miller <davem@davemloft.net> wrote:
>
>
> Eric, please add a proper signoff for yourself, and also please
> add the following tag:
>
> Reported-by: Daniel Jiang <danieljiang0415@gmail.com>


Oh right, will send a v2 immediately. Thanks.

[PATCH v2 net] ping: implement proper locking

[Eric Dumazet]

From: Eric Dumazet <edumazet@google.com>

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>
---
 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 2af6244b83e27ae384e96cf071c10c5a89674804..ccfbce13a6333a65dab64e4847dd510dfafb1b43 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -156,17 +156,18 @@ int 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);
 

Re: [PATCH v2 net] ping: implement proper locking

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 24 Mar 2017 19:36:13 -0700

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

Applied and queued up for -stable, thanks.