[PATCH] can: gs_usb: fixed disconnect bug by removing erroneous use of kfree()

[Marc Kleine-Budde]

From: Maximilain Schneider <m...@schneidersoft.net>

gs_destroy_candev() erroneously calls kfree() on a struct gs_can *, which is
allocated through alloc_candev() and should instead be freed using
free_candev() alone.

The inappropriate use of kfree() causes the kernel to hang when
gs_destroy_candev() is called.

Only the struct gs_usb * which is allocated through kzalloc() should be freed
using kfree() when the device is disconnected.

Signed-off-by: Maximilian Schneider <m...@schneidersoft.net>
Cc: linux-stable <sta...@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <m...@pengutronix.de>
---
 drivers/net/can/usb/gs_usb.c | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
index 5eee62badf45..cbc99d5649af 100644
--- a/drivers/net/can/usb/gs_usb.c
+++ b/drivers/net/can/usb/gs_usb.c
@@ -826,9 +826,8 @@ static struct gs_can *gs_make_candev(unsigned int channel, 
struct usb_interface
 static void gs_destroy_candev(struct gs_can *dev)
 {
        unregister_candev(dev->netdev);
-       free_candev(dev->netdev);
        usb_kill_anchored_urbs(&dev->tx_submitted);
-       kfree(dev);
+       free_candev(dev->netdev);
 }
 
 static int gs_usb_probe(struct usb_interface *intf, const struct usb_device_id 
*id)
@@ -913,12 +912,15 @@ static int gs_usb_probe(struct usb_interface *intf, const 
struct usb_device_id *
        for (i = 0; i < icount; i++) {
                dev->canch[i] = gs_make_candev(i, intf);
                if (IS_ERR_OR_NULL(dev->canch[i])) {
+                       /* save error code to return later */
+                       rc = PTR_ERR(dev->canch[i]);
+
                        /* on failure destroy previously created candevs */
                        icount = i;
-                       for (i = 0; i < icount; i++) {
+                       for (i = 0; i < icount; i++)
                                gs_destroy_candev(dev->canch[i]);
-                               dev->canch[i] = NULL;
-                       }
+
+                       usb_kill_anchored_urbs(&dev->rx_submitted);
                        kfree(dev);
                        return rc;
                }
@@ -939,16 +941,12 @@ static void gs_usb_disconnect(struct usb_interface *intf)
                return;
        }
 
-       for (i = 0; i < GS_MAX_INTF; i++) {
-               struct gs_can *can = dev->canch[i];
-
-               if (!can)
-                       continue;
-
-               gs_destroy_candev(can);
-       }
+       for (i = 0; i < GS_MAX_INTF; i++)
+               if (dev->canch[i])
+                       gs_destroy_candev(dev->canch[i]);
 
        usb_kill_anchored_urbs(&dev->rx_submitted);
+       kfree(dev);
 }
 
 static const struct usb_device_id gs_usb_table[] = {
-- 
2.7.0