cdc-acm: hardening against malicious devices

This should fix the last holes against malicious devices
still open in cdc-acm. It cannot go into stable due to
the introduction of the common parser.
The fix for stable already merged also covers the problems this patch
fixes.
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/class/cdc-acm.c

@@ -1179,6 +1179,9 @@ static int acm_probe(struct usb_interface *intf,
 		return -EINVAL;
 	}
 
+	if (!intf->cur_altsetting)
+		return -EINVAL;
+
 	if (!buflen) {
 		if (intf->cur_altsetting->endpoint &&
 				intf->cur_altsetting->endpoint->extralen &&
@@ -1232,6 +1235,8 @@ static int acm_probe(struct usb_interface *intf,
 		dev_dbg(&intf->dev, "no interfaces\n");
 		return -ENODEV;
 	}
+	if (!data_interface->cur_altsetting || !control_interface->cur_altsetting)
+		return -ENODEV;
 
 	if (data_intf_num != call_intf_num)
 		dev_dbg(&intf->dev, "Separate call control interface. That is not fully supported.\n");