[PATCH v8 5/7] can: isotp: check the return values of can_rx_register() in isotp_bind()

[Oliver Hartkopp <socketcan@hartkopp.net>]

isotp_bind() ignores the return values of can_rx_register() for the RX
and the echo receiver and binds the socket anyway. When a receiver can
not be allocated, bind() succeeds without this receiver, so the socket
does not receive frames or its transmissions time out. isotp_release()
and isotp_notify() later try to remove the missing receiver, which
triggers the "receive list entry not found" warning in
can_rx_unregister().

As the device has been checked before and RTNL prevents a namespace
change during bind(), only -ENOMEM can be returned here.

Check the return values, remove an already registered RX receiver when
the echo receiver can not be registered and return the error.

Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol")
Cc: stable@vger.kernel.org
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---
 net/can/isotp.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/net/can/isotp.c b/net/can/isotp.c
index 1a272ce6a2bd..da80ef606ce0 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -1622,20 +1622,29 @@ static int isotp_bind(struct socket *sock, struct sockaddr_unsized *uaddr, int l
 	if (!(dev->flags & IFF_UP))
 		notify_enetdown = 1;
 
 	ifindex = dev->ifindex;
 
-	if (isotp_register_rxid(so))
-		can_rx_register(net, dev, rx_id, SINGLE_MASK(rx_id),
-				isotp_rcv, sk, sock_i_ino(sk), sk);
+	if (isotp_register_rxid(so)) {
+		err = can_rx_register(net, dev, rx_id, SINGLE_MASK(rx_id),
+				      isotp_rcv, sk, sock_i_ino(sk), sk);
+		if (err)
+			goto out_put_dev;
+	}
 
 	/* no consecutive frame echo skb in flight */
 	WRITE_ONCE(so->cfecho, 0);
 
 	/* register for echo skb's */
-	can_rx_register(net, dev, tx_id, SINGLE_MASK(tx_id),
-			isotp_rcv_echo, sk, sock_i_ino(sk), sk);
+	err = can_rx_register(net, dev, tx_id, SINGLE_MASK(tx_id),
+			      isotp_rcv_echo, sk, sock_i_ino(sk), sk);
+	if (err) {
+		if (isotp_register_rxid(so))
+			can_rx_unregister(net, dev, rx_id, SINGLE_MASK(rx_id),
+					  isotp_rcv, sk);
+		goto out_put_dev;
+	}
 
 	/* switch to new settings */
 	so->ifindex = ifindex;
 	so->rxid = rx_id;
 	so->txid = tx_id;
-- 
2.43.0