[PATCH stable 5.15 2/7] can: isotp: isotp_bind(): return -EINVAL on incorrect CAN ID formatting

[Oliver Hartkopp <socketcan@hartkopp.net>]

commit 2aa39889c463195a0dfe2aff9fad413139c32a4f upstream

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).

Link: https://lore.kernel.org/all/20220515181633.76671-1-socketcan@hartkopp.net
Suggested-by: Derek Will <derekrobertwill@gmail.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 net/can/isotp.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/can/isotp.c b/net/can/isotp.c
index 3e2a7cbade24..b5fdf30a6996 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -1140,10 +1140,15 @@ 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);
 
-- 
2.34.1