[PATCH 5.7 009/124] can: j1939: socket: j1939_sk_bind(): make sure ml_priv is allocated

[Greg Kroah-Hartman]

From: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>

commit af804b7826350d5af728dca4715e473338fbd7e5 upstream.

This patch adds check to ensure that the struct net_device::ml_priv is
allocated, as it is used later by the j1939 stack.

The allocation is done by all mainline CAN network drivers, but when using
bond or team devices this is not the case.

Bail out if no ml_priv is allocated.

Reported-by: syzbot+f03d384f3455d28833eb@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Cc: linux-stable <stable@xxxxxxxxxxxxxxx> # >= v5.4
Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20200807105200.26441-4-o.rempel@xxxxxxxxxxxxxx
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/can/j1939/socket.c |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -466,6 +466,14 @@ static int j1939_sk_bind(struct socket *
 			goto out_release_sock;
 		}
 
+		if (!ndev->ml_priv) {
+			netdev_warn_once(ndev,
+					 "No CAN mid layer private allocated, please fix your driver and use alloc_candev()!\n");
+			dev_put(ndev);
+			ret = -ENODEV;
+			goto out_release_sock;
+		}
+
 		priv = j1939_netdev_start(ndev);
 		dev_put(ndev);
 		if (IS_ERR(priv)) {