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

commit b76b163f46b661499921a0049982764a6659bfe7 upstream

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/can/isotp.c b/net/can/isotp.c
index 19fffa8676f91fd904001e8eaf9c0cdc717e556b..00cb38b4a6f4573dee9b8a02df6f6c4b26871974 100644 (file)
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -1216,7 +1216,8 @@ 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;
 
@@ -1226,24 +1227,28 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
        if (addr->can_family != AF_CAN)
                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;