[PATCH 5.16 0082/1017] can: usb_8dev: usb_8dev_start_xmit(): fix double dev_kfree_skb() in error path

Greg Kroah-Hartman
2022-04-05T11:07:08Z

From: Hangyu Hua <hbh25y@gmail.com>

commit 3d3925ff6433f98992685a9679613a2cc97f3ce2 upstream.

There is no need to call dev_kfree_skb() when usb_submit_urb() fails
because can_put_echo_skb() deletes original skb and
can_free_echo_skb() deletes the cloned skb.

Fixes: 0024d8ad1639 ("can: usb_8dev: Add support for USB2CAN interface from 8 devices")
Link: https://lore.kernel.org/all/20220311080614.45229-1-hbh25y@gmail.com
Cc: stable@vger.kernel.org
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/can/usb/usb_8dev.c | 30 ++++++++++++++----------------
1 file changed, 14 insertions(+), 16 deletions(-)

--- a/drivers/net/can/usb/usb_8dev.c
+++ b/drivers/net/can/usb/usb_8dev.c
@@ -668,9 +668,20 @@ static netdev_tx_t usb_8dev_start_xmit(s
atomic_inc(&priv->active_tx_urbs);

err = usb_submit_urb(urb, GFP_ATOMIC);
- if (unlikely(err))
- goto failed;
- else if (atomic_read(&priv->active_tx_urbs) >= MAX_TX_URBS)
+ if (unlikely(err)) {
+ can_free_echo_skb(netdev, context->echo_index, NULL);
+
+ usb_unanchor_urb(urb);
+ usb_free_coherent(priv->udev, size, buf, urb->transfer_dma);
+
+ atomic_dec(&priv->active_tx_urbs);
+
+ if (err == -ENODEV)
+ netif_device_detach(netdev);
+ else
+ netdev_warn(netdev, "failed tx_urb %d\n", err);
+ stats->tx_dropped++;
+ } else if (atomic_read(&priv->active_tx_urbs) >= MAX_TX_URBS)
/* Slow down tx path */
netif_stop_queue(netdev);

@@ -689,19 +700,6 @@ nofreecontext:

return NETDEV_TX_BUSY;

-failed:
- can_free_echo_skb(netdev, context->echo_index, NULL);
-
- usb_unanchor_urb(urb);
- usb_free_coherent(priv->udev, size, buf, urb->transfer_dma);
-
- atomic_dec(&priv->active_tx_urbs);
-
- if (err == -ENODEV)
- netif_device_detach(netdev);
- else
- netdev_warn(netdev, "failed tx_urb %d\n", err);
-
nomembuf:
usb_free_urb(urb);