rpmsg: virtio: Fix possible double free in rpmsg_probe()

vch will be free in virtio_rpmsg_release_device() when
rpmsg_ns_register_device() fails. There is no need to call kfree() again.

Fix this by changing error path from free_vch to free_ctrldev.

Fixes: c486682 ("rpmsg: virtio: Register the rpmsg_char device")
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
Tested-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Link: https://lore.kernel.org/r/20220426060536.15594-2-hbh25y@gmail.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

drivers/rpmsg/virtio_rpmsg_bus.c

@@ -973,7 +973,8 @@ static int rpmsg_probe(struct virtio_device *vdev)
 
 		err = rpmsg_ns_register_device(rpdev_ns);
 		if (err)
-			goto free_vch;
+			/* vch will be free in virtio_rpmsg_release_device() */
+			goto free_ctrldev;
 	}
 
 	/*
@@ -997,8 +998,6 @@ static int rpmsg_probe(struct virtio_device *vdev)
 
 	return 0;
 
-free_vch:
-	kfree(vch);
 free_ctrldev:
 	rpmsg_virtio_del_ctrl_dev(rpdev_ctrl);
 free_coherent: