can: isotp: recvmsg(): allow MSG_CMSG_COMPAT flag

JIRA: https://issues.redhat.com/browse/RHEL-80832

commit db2773d
Author: Oliver Hartkopp <[email protected]>
Date:   Thu Apr 6 13:08:45 2023 +0200

    can: isotp: recvmsg(): allow MSG_CMSG_COMPAT flag

    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: hartkopp/can-isotp#59
    Cc: Oleksij Rempel <[email protected]>
    Suggested-by: Marc Kleine-Budde <[email protected]>
    Signed-off-by: Oliver Hartkopp <[email protected]>
    Fixes: 42bf50a ("can: isotp: support MSG_TRUNC flag when reading from socket")
    Link: https://lore.kernel.org/[email protected]
    Cc: [email protected]
    Signed-off-by: Marc Kleine-Budde <[email protected]>

Signed-off-by: Radu Rendec <[email protected]>

Author: rrendec

net/can/isotp.c

@@ -1107,7 +1107,7 @@ static int isotp_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
 	struct isotp_sock *so = isotp_sk(sk);
 	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)