can: gs_usb: gs_can_open(): fix race dev->can.state condition

The dev->can.state is set to CAN_STATE_ERROR_ACTIVE, after the device
has been started. On busy networks the CAN controller might receive
CAN frame between and go into an error state before the dev->can.state
is assigned.

Assign dev->can.state before starting the controller to close the race
window.

Fixes: d08e973a77d1 ("can: gs_usb: Added support for the GS_USB CAN devices")
Link: https://lore.kernel.org/all/20220920195216.232481-1-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
index baf749c8cda3f5fb68be38625aa75b0d02fb6b81..553e2c7b0b12152873cace7e2069b617c44da92f 100644 (file)
--- a/drivers/net/can/usb/gs_usb.c
+++ b/drivers/net/can/usb/gs_usb.c
@@ -824,6 +824,7 @@ static int gs_can_open(struct net_device *netdev)
                flags |= GS_CAN_MODE_TRIPLE_SAMPLE;
 
        /* finally start device */
+       dev->can.state = CAN_STATE_ERROR_ACTIVE;
        dm->mode = cpu_to_le32(GS_CAN_MODE_START);
        dm->flags = cpu_to_le32(flags);
        rc = usb_control_msg(interface_to_usbdev(dev->iface),
@@ -835,13 +836,12 @@ static int gs_can_open(struct net_device *netdev)
        if (rc < 0) {
                netdev_err(netdev, "Couldn't start device (err=%d)\n", rc);
                kfree(dm);
+               dev->can.state = CAN_STATE_STOPPED;
                return rc;
        }
 
        kfree(dm);
 
-       dev->can.state = CAN_STATE_ERROR_ACTIVE;
-
        parent->active_channels++;
        if (!(dev->can.ctrlmode & CAN_CTRLMODE_LISTENONLY))
                netif_start_queue(netdev);