can: peak: fix bad memory access and free sequence

commit b67d0dd7d0dc9e456825447bbeb935d8ef43ea7c upstream.

Fix for bad memory access while disconnecting. netdev is freed before
private data free, and dev is accessed after freeing netdev.

This makes a slub problem, and it raise kernel oops with slub debugger
config.

Signed-off-by: Jiho Chu <jiho.chu@samsung.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb_core.c b/drivers/net/can/usb/peak_usb/pcan_usb_core.c
index 3a220d2f2ee1b47763eefbe73e7944e94debb056..9a82890f64e5888e7561f6b11cfbc6e08b692a5a 100644 (file)
--- a/drivers/net/can/usb/peak_usb/pcan_usb_core.c
+++ b/drivers/net/can/usb/peak_usb/pcan_usb_core.c
@@ -817,23 +817,25 @@ lbl_free_candev:
 static void peak_usb_disconnect(struct usb_interface *intf)
 {
        struct peak_usb_device *dev;
+       struct peak_usb_device *dev_prev_siblings;
 
        /* unregister as many netdev devices as siblings */
-       for (dev = usb_get_intfdata(intf); dev; dev = dev->prev_siblings) {
+       for (dev = usb_get_intfdata(intf); dev; dev = dev_prev_siblings) {
                struct net_device *netdev = dev->netdev;
                char name[IFNAMSIZ];
 
+               dev_prev_siblings = dev->prev_siblings;
                dev->state &= ~PCAN_USB_STATE_CONNECTED;
                strncpy(name, netdev->name, IFNAMSIZ);
 
                unregister_netdev(netdev);
-               free_candev(netdev);
 
                kfree(dev->cmd_buf);
                dev->next_siblings = NULL;
                if (dev->adapter->dev_free)
                        dev->adapter->dev_free(dev);
 
+               free_candev(netdev);
                dev_info(&intf->dev, "%s removed\n", name);
        }