[PATCH] media: rp1-cfe: Fix double-free on video device re-registration

[Xiaolei Wang <xiaolei.wang@windriver.com>]

When a sensor driver is unloaded and reloaded (e.g., rmmod/insmod ov5647),
the cfe_async_complete callback is invoked again, attempting to re-register
video nodes that are still registered. This causes multiple issues:

1. KASAN double-free in kfree_const when dev_set_name tries to free the
   kobject name that was already freed during video_unregister_device
2. "tried to init an initialized object" warnings because the video_device
   kobject is re-initialized before being fully released

Fix this by:
- Adding a check in cfe_probe_complete() to skip nodes already in
  NODE_REGISTERED state, preventing duplicate registration attempts
- Implementing cfe_async_unbind() callback to properly clear the
  source_sd pointer when the subdevice is unbound

Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>
---
 drivers/media/platform/raspberrypi/rp1-cfe/cfe.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/media/platform/raspberrypi/rp1-cfe/cfe.c b/drivers/media/platform/raspberrypi/rp1-cfe/cfe.c
index 62dca76b468d..d3813c79316d 100644
--- a/drivers/media/platform/raspberrypi/rp1-cfe/cfe.c
+++ b/drivers/media/platform/raspberrypi/rp1-cfe/cfe.c
@@ -2152,6 +2152,9 @@ static int cfe_probe_complete(struct cfe_device *cfe)
 	cfe->v4l2_dev.notify = cfe_notify;
 
 	for (unsigned int i = 0; i < NUM_NODES; i++) {
+		if (check_state(cfe, NODE_REGISTERED, i))
+			continue;
+
 		ret = cfe_register_node(cfe, i);
 		if (ret) {
 			cfe_err(cfe, "Unable to register video node %u.\n", i);
@@ -2204,8 +2207,19 @@ static int cfe_async_complete(struct v4l2_async_notifier *notifier)
 	return cfe_probe_complete(cfe);
 }
 
+static void cfe_async_unbind(struct v4l2_async_notifier *notifier,
+			     struct v4l2_subdev *subdev,
+			     struct v4l2_async_connection *asd)
+{
+	struct cfe_device *cfe = to_cfe_device(notifier->v4l2_dev);
+
+	cfe->source_sd = NULL;
+	cfe_info(cfe, "Unbinding subdev %s\n", subdev->name);
+}
+
 static const struct v4l2_async_notifier_operations cfe_async_ops = {
 	.bound = cfe_async_bound,
+	.unbind = cfe_async_unbind,
 	.complete = cfe_async_complete,
 };
 
-- 
2.43.0