[PATCH 5.19 144/207] can: gs_usb: gs_can_open(): fix race dev->can.state condition

Greg Kroah-Hartman
2022-09-26T11:51:23Z

From: Marc Kleine-Budde <mkl@pengutronix.de>

[ Upstream commit 5440428b3da65408dba0241985acb7a05258b85e ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/can/usb/gs_usb.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
index d3a658b444b5..092cd51b3926 100644
--- 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);
--
2.35.1