1 files changed, 11 insertions, 2 deletions

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index 86292e6aaf49..1a482344b3f5 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -185,7 +185,6 @@ enum rx_ctrl_state{
 #define BM_REQUEST_TYPE (0xa1)
 #define B_NOTIFICATION  (0x20)
 #define W_VALUE         (0x0)
-#define W_INDEX         (0x2)
 #define W_LENGTH        (0x2)
 
 #define B_OVERRUN       (0x1<<6)
@@ -1487,6 +1486,7 @@ static void tiocmget_intr_callback(struct urb *urb)
         struct uart_icount *icount;
         struct hso_serial_state_notification *serial_state_notification;
         struct usb_device *usb;
+        int if_num;
 
         /* Sanity checks */
         if (!serial)
@@ -1495,15 +1495,24 @@ static void tiocmget_intr_callback(struct urb *urb)
                 handle_usb_error(status, __func__, serial->parent);
                 return;
         }
+
+        /* tiocmget is only supported on HSO_PORT_MODEM */
         tiocmget = serial->tiocmget;
         if (!tiocmget)
                 return;
+        BUG_ON((serial->parent->port_spec & HSO_PORT_MASK) != HSO_PORT_MODEM);
+
         usb = serial->parent->usb;
+        if_num = serial->parent->interface->altsetting->desc.bInterfaceNumber;
+
+        /* wIndex should be the USB interface number of the port to which the
+         * notification applies, which should always be the Modem port.
+         */
         serial_state_notification = &tiocmget->serial_state_notification;
         if (serial_state_notification->bmRequestType != BM_REQUEST_TYPE ||
             serial_state_notification->bNotification != B_NOTIFICATION ||
             le16_to_cpu(serial_state_notification->wValue) != W_VALUE ||
-            le16_to_cpu(serial_state_notification->wIndex) != W_INDEX ||
+            le16_to_cpu(serial_state_notification->wIndex) != if_num ||
             le16_to_cpu(serial_state_notification->wLength) != W_LENGTH) {
                 dev_warn(&usb->dev,
                          "hso received invalid serial state notification\n");