linux-kernel - [PATCH 5.4 1/1] can: usb_8dev: usb_8dev_start_xmit(): fix double dev_kfree

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Date:   Tue, 19 Apr 2022 14:28:21 +0300
From:   Dragos-Marian Panait <dragos.panait@...driver.com>
To:     <stable@...r.kernel.org>
CC:     <dragos.panait@...driver.com>, <wg@...ndegger.com>,
        <mkl@...gutronix.de>, <davem@...emloft.net>,
        <paskripkin@...il.com>, <gregkh@...uxfoundation.org>,
        <hbh25y@...il.com>, <linux-can@...r.kernel.org>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH 5.4 1/1] can: usb_8dev: usb_8dev_start_xmit(): fix double dev_kfree_skb() in error path

From: Hangyu Hua <hbh25y@...il.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@...r.kernel.org
Signed-off-by: Hangyu Hua <hbh25y@...il.com>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
[DP: adjusted params of can_free_echo_skb() for 5.4 stable]
Signed-off-by: Dragos-Marian Panait <dragos.panait@...driver.com>
---
 drivers/net/can/usb/usb_8dev.c | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/drivers/net/can/usb/usb_8dev.c b/drivers/net/can/usb/usb_8dev.c
index c43e98bb6e2d..b514b2eaa318 100644
--- a/drivers/net/can/usb/usb_8dev.c
+++ b/drivers/net/can/usb/usb_8dev.c
@@ -670,9 +670,20 @@ static netdev_tx_t usb_8dev_start_xmit(struct sk_buff *skb,
 	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);
+
+		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);
 
@@ -691,19 +702,6 @@ static netdev_tx_t usb_8dev_start_xmit(struct sk_buff *skb,
 
 	return NETDEV_TX_BUSY;
 
-failed:
-	can_free_echo_skb(netdev, context->echo_index);
-
-	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);
 
-- 
2.17.1