: media : hackrf : memory leak

Due to a missing v4l2_device_get function in the hackrf_probe function, the reference count of the v4l2_device object reaches zero inside the wrong API function (video_unregister_device) instead of v4l2_device_put. This causes a memory leak as the release callback would not get called.

---

@@ -1524,6 +1524,7 @@ static int hackrf_probe(struct usb_inter

  "Failed to register as video device (%d)\n", ret); goto err_video_unregister_device_rx;
  }
+ v4l2_device_get(&dev->v4l2_dev);
  dev_info(dev->dev, "Registered as %s\n", video_device_node_name(&dev->tx_vdev));​

Hi Tuba,

The refcount is 1 after calling v4l2_device_register(). Each video_register_device call will increment the refcount by 1. When a video node is released (v4l2_device_release) the refcount is decremented, and when the device is disconnected (hackrf_disconnect) the refcount is decremented again.

So I don't see where there is a memory leak, and neither do I understand how incrementing the refcount would prevent a memory leak. I would expect that it causes a memory leak!

Is there something else going on here?

Regards,

Hans

Hi Hans,

You are right..

This was a false positive due to a bug in my environment model. Obviously, v4l2_device_disconnect does not affect the v4l2_device reference count.

Best,

Tuba
________________________________________
From: Hans Verkuil <[email protected]>
Sent: Monday, January 28, 2019 9:10 AM
To: Yavuz, Tuba; [email protected]
Cc: Greg KH
Subject: Re: [PATCH] : media : hackrf : memory leak

Hi Tuba,

The refcount is 1 after calling v4l2_device_register(). Each video_register_device call will increment the refcount by 1. When a video node is released (v4l2_device_release) the refcount is decremented, and when the device is disconnected (hackrf_disconnect) the refcount is decremented again.

So I don't see where there is a memory leak, and neither do I understand how incrementing the refcount would prevent a memory leak. I would expect that it causes a memory leak!

Is there something else going on here?

Regards,

Hans