staging: rtl8712: fix interface sanity check

commit c724f776f048538ecfdf53a52b7a522309f5c504 upstream.

Make sure to use the current alternate setting when verifying the
interface descriptors to avoid binding to an invalid interface.

Failing to do so could cause the driver to misbehave or trigger a WARN()
in usb_submit_urb() that kernels with panic_on_warn set would choke on.

Fixes: 2865d42c ("staging: r8712u: Add the new driver to the mainline kernel")
Cc: stable <stable@vger.kernel.org>     # 2.6.37
Signed-off-by: NJohan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20191210114751.5119-3-johan@kernel.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/staging/rtl8712/usb_intf.c

@@ -275,7 +275,7 @@ static uint r8712_usb_dvobj_init(struct _adapter *padapter)
 
 	pdvobjpriv->padapter = padapter;
 	padapter->EepromAddressSize = 6;
-	phost_iface = &pintf->altsetting[0];
+	phost_iface = pintf->cur_altsetting;
 	piface_desc = &phost_iface->desc;
 	pdvobjpriv->nr_endpoint = piface_desc->bNumEndpoints;
 	if (pusbd->speed == USB_SPEED_HIGH) {