can: isotp: recvmsg(): allow MSG_CMSG_COMPAT flag

commit db2773d65b02aed319a93efdfb958087771d4e19 upstream.

The control message provided by isotp support MSG_CMSG_COMPAT but
blocked recvmsg() syscalls that have set this flag, i.e. on 32bit user
space on 64 bit kernels.

Link: https://github.com/hartkopp/can-isotp/issues/59
Cc: Oleksij Rempel <o.rempel@pengutronix.de>
Suggested-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Fixes: 42bf50a1795a ("can: isotp: support MSG_TRUNC flag when reading from socket")
Link: https://lore.kernel.org/20230505110308.81087-2-mkl@pengutronix.de
Cc: stable@vger.kernel.org
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 4360f33278c1e4f4f7ee58ed898e38975d589d39..4fcd8162fad4aa5596ad10953c1c38ef6a6eafe4 100644 (file)
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -1016,7 +1016,7 @@ static int isotp_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
        int noblock = flags & MSG_DONTWAIT;
        int ret = 0;
 
-       if (flags & ~(MSG_DONTWAIT | MSG_TRUNC | MSG_PEEK))
+       if (flags & ~(MSG_DONTWAIT | MSG_TRUNC | MSG_PEEK | MSG_CMSG_COMPAT))
                return -EINVAL;
 
        if (!so->bound)