net: cdc_ncm: only the control intf can be probed

The probed interface must be the master/control interface of the
function.  Make this explicit and simplify redundant tests.

Cc: Alexey Orishko <alexey.orishko@gmail.com>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index 435fcc75d706b468f1e4eadf2b1c0f45cbfc33a4..5aa3e60851d0f76a0092c6edba9f7e3ff91ce9e7 100644 (file)
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -394,6 +394,9 @@ int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, u8 data_
        /* store ctx pointer in device data field */
        dev->data[0] = (unsigned long)ctx;
 
+       /* only the control interface can be successfully probed */
+       ctx->control = intf;
+
        /* get some pointers */
        driver = driver_of(intf);
        buf = intf->cur_altsetting->extra;
@@ -411,9 +414,10 @@ int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, u8 data_
                                break;
 
                        union_desc = (const struct usb_cdc_union_desc *)buf;
-
-                       ctx->control = usb_ifnum_to_if(dev->udev,
-                                                      union_desc->bMasterInterface0);
+                       /* the master must be the interface we are probing */
+                       if (intf->cur_altsetting->desc.bInterfaceNumber !=
+                           union_desc->bMasterInterface0)
+                               goto error;
                        ctx->data = usb_ifnum_to_if(dev->udev,
                                                    union_desc->bSlaveInterface0);
                        break;
@@ -459,14 +463,12 @@ advance:
 
        /* some buggy devices have an IAD but no CDC Union */
        if (!union_desc && intf->intf_assoc && intf->intf_assoc->bInterfaceCount == 2) {
-               ctx->control = intf;
                ctx->data = usb_ifnum_to_if(dev->udev, intf->cur_altsetting->desc.bInterfaceNumber + 1);
                dev_dbg(&intf->dev, "CDC Union missing - got slave from IAD\n");
        }
 
        /* check if we got everything */
-       if ((ctx->control == NULL) || (ctx->data == NULL) ||
-           ((!ctx->mbim_desc) && ((ctx->ether_desc == NULL) || (ctx->control != intf))))
+       if (!ctx->data || (!ctx->mbim_desc && !ctx->ether_desc))
                goto error;
 
        /* claim data interface, if different from control */