media: rc: do not access device via sysfs after rc_unregister_device()

commit a2e2d73f upstream.

Device drivers do not expect to have change_protocol or wakeup
re-programming to be accesed after rc_unregister_device(). This can
cause the device driver to access deallocated resources.

Cc: <stable@vger.kernel.org> # 4.16+
Signed-off-by: NSean Young <sean@mess.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/media/rc/rc-main.c

@@ -1245,6 +1245,10 @@ static ssize_t store_protocols(struct device *device,
 	}
 
 	mutex_lock(&dev->lock);
+	if (!dev->registered) {
+		mutex_unlock(&dev->lock);
+		return -ENODEV;
+	}
 
 	old_protocols = *current_protocols;
 	new_protocols = old_protocols;
@@ -1383,6 +1387,10 @@ static ssize_t store_filter(struct device *device,
 		return -EINVAL;
 
 	mutex_lock(&dev->lock);
+	if (!dev->registered) {
+		mutex_unlock(&dev->lock);
+		return -ENODEV;
+	}
 
 	new_filter = *filter;
 	if (fattr->mask)
@@ -1497,6 +1505,10 @@ static ssize_t store_wakeup_protocols(struct device *device,
 	int i;
 
 	mutex_lock(&dev->lock);
+	if (!dev->registered) {
+		mutex_unlock(&dev->lock);
+		return -ENODEV;
+	}
 
 	allowed = dev->allowed_wakeup_protocols;