[PATCH 2/6] can: j1939: transport: j1939_simple_recv(): ignore local J1939 messages send not by J1939 stack

[Marc Kleine-Budde <mkl@pengutronix.de>]

From: Oleksij Rempel <o.rempel@pengutronix.de>

In current J1939 stack implementation, we process all locally send
messages as own messages. Even if it was send by CAN_RAW socket.

To reproduce it use following commands:
testj1939 -P -r can0:0x80 &
cansend can0 18238040#0123

This step will trigger false positive not critical warning:
j1939_simple_recv: Received already invalidated message

With this patch we add additional check to make sure, related skb is own
echo message.

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20200807105200.26441-2-o.rempel@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 net/can/j1939/socket.c    | 1 +
 net/can/j1939/transport.c | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index b634b680177f..ad973370de12 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -398,6 +398,7 @@ static int j1939_sk_init(struct sock *sk)
 	spin_lock_init(&jsk->sk_session_queue_lock);
 	INIT_LIST_HEAD(&jsk->sk_session_queue);
 	sk->sk_destruct = j1939_sk_sock_destruct;
+	sk->sk_protocol = CAN_J1939;
 
 	return 0;
 }
diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index 9f99af5b0b11..b135c5e2a86e 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -2017,6 +2017,10 @@ void j1939_simple_recv(struct j1939_priv *priv, struct sk_buff *skb)
 	if (!skb->sk)
 		return;
 
+	if (skb->sk->sk_family != AF_CAN ||
+	    skb->sk->sk_protocol != CAN_J1939)
+		return;
+
 	j1939_session_list_lock(priv);
 	session = j1939_session_get_simple(priv, skb);
 	j1939_session_list_unlock(priv);
-- 
2.28.0