um: virtio_uml: Fix use-after-free after put_device in probe

When register_virtio_device() fails in virtio_uml_probe(),
the code sets vu_dev->registered = 1 even though
the device was not successfully registered.
This can lead to use-after-free or other issues.

Fixes: 04e5b1f ("um: virtio: Remove device on disconnect")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Author: Yuuoniy

arch/um/drivers/virtio_uml.c

@@ -1250,10 +1250,12 @@ static int virtio_uml_probe(struct platform_device *pdev)
 	device_set_wakeup_capable(&vu_dev->vdev.dev, true);
 
 	rc = register_virtio_device(&vu_dev->vdev);
-	if (rc)
+	if (rc) {
 		put_device(&vu_dev->vdev.dev);
+		return rc;
+	}
 	vu_dev->registered = 1;
-	return rc;
+	return 0;
 
 error_init:
 	os_close_file(vu_dev->sock);