[PATCH 01/20] can: raw: check for CAN FD capable netdev in raw_sendmsg()

[Marc Kleine-Budde]

From: Oliver Hartkopp <socket...@hartkopp.net>

When the socket is CAN FD enabled it can handle CAN FD frame
transmissions.  Add an additional check in raw_sendmsg() as a CAN2.0 CAN
driver (non CAN FD) should never see a CAN FD frame. Due to the commonly
used can_dropped_invalid_skb() function the CAN 2.0 driver would drop
that CAN FD frame anyway - but with this patch the user gets a proper
-EINVAL return code.

Signed-off-by: Oliver Hartkopp <socket...@hartkopp.net>
Cc: linux-stable <sta...@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <m...@pengutronix.de>
---
 net/can/raw.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/net/can/raw.c b/net/can/raw.c
index 1051eee82581..3aab7664933f 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -745,18 +745,19 @@ static int raw_sendmsg(struct socket *sock, struct msghdr 
*msg, size_t size)
        } else
                ifindex = ro->ifindex;
 
-       if (ro->fd_frames) {
+       dev = dev_get_by_index(sock_net(sk), ifindex);
+       if (!dev)
+               return -ENXIO;
+
+       err = -EINVAL;
+       if (ro->fd_frames && dev->mtu == CANFD_MTU) {
                if (unlikely(size != CANFD_MTU && size != CAN_MTU))
-                       return -EINVAL;
+                       goto put_dev;
        } else {
                if (unlikely(size != CAN_MTU))
-                       return -EINVAL;
+                       goto put_dev;
        }
 
-       dev = dev_get_by_index(sock_net(sk), ifindex);
-       if (!dev)
-               return -ENXIO;
-
        skb = sock_alloc_send_skb(sk, size + sizeof(struct can_skb_priv),
                                  msg->msg_flags & MSG_DONTWAIT, &err);
        if (!skb)
-- 
2.19.1