usbip: vudc: fix null pointer dereference on udc->lock

Currently the driver attempts to spin lock on udc->lock before a NULL
pointer check is performed on udc, hence there is a potential null
pointer dereference on udc->lock.  Fix this by moving the null check
on udc before the lock occurs.

Fixes: ea6873a45a22 ("usbip: vudc: Add SysFS infrastructure for VUDC")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Shuah Khan <shuahkh@osg.samsung.com>
Reviewed-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/usb/usbip/vudc_sysfs.c b/drivers/usb/usbip/vudc_sysfs.c
index d86f72bbbb91..6dcd3ff655c3 100644
--- a/drivers/usb/usbip/vudc_sysfs.c
+++ b/drivers/usb/usbip/vudc_sysfs.c
@@ -105,10 +105,14 @@ static ssize_t usbip_sockfd_store(struct device *dev, struct device_attribute *a
         if (rv != 0)
                 return -EINVAL;
 
+        if (!udc) {
+                dev_err(dev, "no device");
+                return -ENODEV;
+        }
         spin_lock_irqsave(&udc->lock, flags);
         /* Don't export what we don't have */
-        if (!udc || !udc->driver || !udc->pullup) {
-                dev_err(dev, "no device or gadget not bound");
+        if (!udc->driver || !udc->pullup) {
+                dev_err(dev, "gadget not bound");
                 ret = -ENODEV;
                 goto unlock;
         }