Bluetooth: Check for valid HCI UART driver flags

Providing unknown or invalid flags to the HCI UART driver should
result in an error. So check which flags are valid and otherwise
return an error.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

drivers/bluetooth/hci_ldisc.c

@@ -477,6 +477,21 @@ static int hci_uart_set_proto(struct hci_uart *hu, int id)
 	return 0;
 }
 
+static int hci_uart_set_flags(struct hci_uart *hu, unsigned long flags)
+{
+	unsigned long valid_flags = BIT(HCI_UART_RAW_DEVICE) |
+				    BIT(HCI_UART_RESET_ON_INIT) |
+				    BIT(HCI_UART_CREATE_AMP) |
+				    BIT(HCI_UART_INIT_PENDING);
+
+	if ((flags & ~valid_flags))
+		return -EINVAL;
+
+	hu->hdev_flags = flags;
+
+	return 0;
+}
+
 /* hci_uart_tty_ioctl()
  *
  *    Process IOCTL system call for the tty device.
@@ -527,7 +542,9 @@ static int hci_uart_tty_ioctl(struct tty_struct *tty, struct file * file,
 	case HCIUARTSETFLAGS:
 		if (test_bit(HCI_UART_PROTO_SET, &hu->flags))
 			return -EBUSY;
-		hu->hdev_flags = arg;
+		err = hci_uart_set_flags(hu, arg);
+		if (err)
+			return err;
 		break;
 
 	case HCIUARTGETFLAGS: