USB: Avoid NULL pointer deref in usb_hcd_alloc_bandwidth.

usb_ifnum_to_if() can return NULL if the USB device does not have a
configuration installed (usb_device->actconfig == NULL), or if we can't
find the interface number in the installed configuration.  Return an
error instead of crashing.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 8669ba3..73cbbd8 100644 (file)
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1775,6 +1775,8 @@ int usb_hcd_alloc_bandwidth(struct usb_device *udev,
                struct usb_interface *iface = usb_ifnum_to_if(udev,
                                cur_alt->desc.bInterfaceNumber);
 
+               if (!iface)
+                       return -EINVAL;
                if (iface->resetting_device) {
                        /*
                         * The USB core just reset the device, so the xHCI host