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

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 <max@schneidersoft.net>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

1 files 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[] = {