USB: cdc-acm: fix sysfs attribute registration bug

This patch (as950) fixes a bug in the cdc-acm driver. It doesn't keep
track of which interface (control or data) the sysfs attributes get
registered for, and as a result, during disconnect it will sometimes
attempt to remove the attributes from the wrong interface. The
left-over attributes can cause a crash later on, particularly if the driver
module has been unloaded.

Signed-off-by: Alan Stern <[e-mail]>
Acked-by: Oliver Neukum <[e-mail]>
Cc: stable <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/class/cdc-acm.c

···
 			return -EINVAL;
 		}
 	}
+
+	/* Accept probe requests only for the control interface */
+	if (intf != control_interface)
+		return -ENODEV;
 	
 	if (usb_interface_claimed(data_interface)) { /* valid in this context */
 		dev_dbg(&intf->dev,"The data interface isn't available");
···
 		return;
 	}
 	if (acm->country_codes){
-		device_remove_file(&intf->dev, &dev_attr_wCountryCodes);
-		device_remove_file(&intf->dev, &dev_attr_iCountryCodeRelDate);
+		device_remove_file(&acm->control->dev,
+				&dev_attr_wCountryCodes);
+		device_remove_file(&acm->control->dev,
+				&dev_attr_iCountryCodeRelDate);
 	}
-	device_remove_file(&intf->dev, &dev_attr_bmCapabilities);
+	device_remove_file(&acm->control->dev, &dev_attr_bmCapabilities);
 	acm->dev = NULL;
 	usb_set_intfdata(acm->control, NULL);
 	usb_set_intfdata(acm->data, NULL);