caif_usb: Check driver name before reading driver state in netdev notifier

In cfusbl_device_notify(), the usbnet and usbdev variables are
initialised before the driver name has been checked.  In case the
device's driver is not cdc_ncm, this may result in reading beyond the
end of the netdev private area.  Move the initialisation below the
driver name check.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 2 deletions

diff --git a/net/caif/caif_usb.c b/net/caif/caif_usb.c
index fd7cbf5aa895..582f80c8ef3d 100644
--- a/net/caif/caif_usb.c
+++ b/net/caif/caif_usb.c
@@ -126,8 +126,8 @@ static int cfusbl_device_notify(struct notifier_block *me, unsigned long what,
         struct net_device *dev = arg;
         struct caif_dev_common common;
         struct cflayer *layer, *link_support;
-        struct usbnet   *usbnet = netdev_priv(dev);
-        struct usb_device       *usbdev = usbnet->udev;
+        struct usbnet *usbnet;
+        struct usb_device *usbdev;
         struct ethtool_drvinfo drvinfo;
 
         /*
@@ -141,6 +141,9 @@ static int cfusbl_device_notify(struct notifier_block *me, unsigned long what,
         if (strncmp(drvinfo.driver, "cdc_ncm", 7) != 0)
                 return 0;
 
+        usbnet = netdev_priv(dev);
+        usbdev = usbnet->udev;
+
         pr_debug("USB CDC NCM device VID:0x%4x PID:0x%4x\n",
                 le16_to_cpu(usbdev->descriptor.idVendor),
                 le16_to_cpu(usbdev->descriptor.idProduct));