linux-kernel - [PATCH 4.19 32/91] can: peak_usb: fix potential double kfree

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Message-Id: <20190814165751.055919064@linuxfoundation.org>
Date:   Wed, 14 Aug 2019 19:00:55 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Stephane Grosjean <s.grosjean@...k-system.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH 4.19 32/91] can: peak_usb: fix potential double kfree_skb()

From: Stephane Grosjean <s.grosjean@...k-system.com>

commit fee6a8923ae0d318a7f7950c6c6c28a96cea099b upstream.

When closing the CAN device while tx skbs are inflight, echo skb could
be released twice. By calling close_candev() before unlinking all
pending tx urbs, then the internal echo_skb[] array is fully and
correctly cleared before the USB write callback and, therefore,
can_get_echo_skb() are called, for each aborted URB.

Fixes: bb4785551f64 ("can: usb: PEAK-System Technik USB adapters driver core")
Signed-off-by: Stephane Grosjean <s.grosjean@...k-system.com>
Cc: linux-stable <stable@...r.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/can/usb/peak_usb/pcan_usb_core.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/net/can/usb/peak_usb/pcan_usb_core.c
+++ b/drivers/net/can/usb/peak_usb/pcan_usb_core.c
@@ -576,16 +576,16 @@ static int peak_usb_ndo_stop(struct net_
 	dev->state &= ~PCAN_USB_STATE_STARTED;
 	netif_stop_queue(netdev);
 
+	close_candev(netdev);
+
+	dev->can.state = CAN_STATE_STOPPED;
+
 	/* unlink all pending urbs and free used memory */
 	peak_usb_unlink_all_urbs(dev);
 
 	if (dev->adapter->dev_stop)
 		dev->adapter->dev_stop(dev);
 
-	close_candev(netdev);
-
-	dev->can.state = CAN_STATE_STOPPED;
-
 	/* can set bus off now */
 	if (dev->adapter->dev_set_bus) {
 		int err = dev->adapter->dev_set_bus(dev, 0);