can: isotp: return -EINVAL on incorrect CAN ID formatting

Commit 3ea566422cbd ("can: isotp: sanitize CAN ID checks in isotp_bind()") checks the given CAN ID address information by sanitizing the input values.

This check (silently) removes obsolete bits by masking the given CAN IDs.

Derek Will suggested to give a feedback to the application programmer when the 'sanitizing' was actually needed which means the programmer provided CAN ID content in a wrong format (e.g. SFF CAN IDs with a CAN ID > 0x7FF).

---
 net/can/isotp.c | 5 +++++
 1 file changed, 5 insertions(+)

index 2caeeae8ec16..4a4007f10970 100644
@@ -1230,10 +1230,15 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
 	if (rx_id & CAN_EFF_FLAG)
 		rx_id &= (CAN_EFF_FLAG | CAN_EFF_MASK);
 	else
 		rx_id &= CAN_SFF_MASK;
 
+	/* give feedback on wrong CAN-ID values */
+	if (tx_id != addr->can_addr.tp.tx_id ||
+	    rx_id != addr->can_addr.tp.rx_id)
+		return -EINVAL;
+
 	if (!addr->can_ifindex)
 		return -ENODEV;
 
 	lock_sock(sk);
 

2.30.2