can: isotp: isotp_bind(): do not validate unused address information

With commit 2aa39889c463 ("can: isotp: isotp_bind(): return -EINVAL on
incorrect CAN ID formatting") the bind() syscall returns -EINVAL when
the given CAN ID needed to be sanitized. But in the case of an unconfirmed
broadcast mode the rx CAN ID is not needed and may be uninitialized from
the caller - which is ok.

This patch makes sure the result of an inproper CAN ID format is only
provided when the address information is needed.

Link: https://lore.kernel.org/all/20220517145653.2556-1-socketcan@hartkopp.net
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/net/can/isotp.c b/net/can/isotp.c
index 4a4007f10970e04171b620f67a7f78ffad8d1143..43a27d19cdacfddeace6d7a740b0531ab4c31b96 100644 (file)
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -1212,31 +1212,36 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
        struct net *net = sock_net(sk);
        int ifindex;
        struct net_device *dev;
-       canid_t tx_id, rx_id;
+       canid_t tx_id = addr->can_addr.tp.tx_id;
+       canid_t rx_id = addr->can_addr.tp.rx_id;
        int err = 0;
        int notify_enetdown = 0;
 
        if (len < ISOTP_MIN_NAMELEN)
                return -EINVAL;
 
-       /* sanitize tx/rx CAN identifiers */
-       tx_id = addr->can_addr.tp.tx_id;
+       /* sanitize tx CAN identifier */
        if (tx_id & CAN_EFF_FLAG)
                tx_id &= (CAN_EFF_FLAG | CAN_EFF_MASK);
        else
                tx_id &= CAN_SFF_MASK;
 
-       rx_id = addr->can_addr.tp.rx_id;
-       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)
+       /* give feedback on wrong CAN-ID value */
+       if (tx_id != addr->can_addr.tp.tx_id)
                return -EINVAL;
 
+       /* sanitize rx CAN identifier (if needed) */
+       if (isotp_register_rxid(so)) {
+               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 value */
+               if (rx_id != addr->can_addr.tp.rx_id)
+                       return -EINVAL;
+       }
+
        if (!addr->can_ifindex)
                return -ENODEV;