Input: ims-pcu - sanity check against missing interfaces

A malicious device missing interface can make the driver oops.
Add sanity checking.

Signed-off-by: Oliver Neukum <ONeukum@suse.com>
CC: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/misc/ims-pcu.c

@@ -1663,6 +1663,8 @@ static int ims_pcu_parse_cdc_data(struct usb_interface *intf, struct ims_pcu *pc
 
 	pcu->ctrl_intf = usb_ifnum_to_if(pcu->udev,
 					 union_desc->bMasterInterface0);
+	if (!pcu->ctrl_intf)
+		return -EINVAL;
 
 	alt = pcu->ctrl_intf->cur_altsetting;
 	pcu->ep_ctrl = &alt->endpoint[0].desc;
@@ -1670,6 +1672,8 @@ static int ims_pcu_parse_cdc_data(struct usb_interface *intf, struct ims_pcu *pc
 
 	pcu->data_intf = usb_ifnum_to_if(pcu->udev,
 					 union_desc->bSlaveInterface0);
+	if (!pcu->data_intf)
+		return -EINVAL;
 
 	alt = pcu->data_intf->cur_altsetting;
 	if (alt->desc.bNumEndpoints != 2) {