On Thu, Jul 31, 2025 at 03:19:19AM +0100, Salah Triki wrote:
The driver stores a reference to the `usb_device` structure (`udev`) in its private data (`data->udev`), which can persist beyond the immediate context of the `bfusb_probe()` function.
Without proper reference count management, this can lead to two issues:
- A `use-after-free` scenario if `udev` is accessed after its main reference count drops to zero (e.g., if the device is disconnected and the `data` structure is still active).
How can that happen as during the probe/remove cycle, the reference count is always properly incremetned.
- A `memory leak` if `udev`'s reference count is not properly decremented during driver disconnect, preventing the `usb_device` object from being freed.
There is no leak here at all, sorry.
To correctly manage the `udev` lifetime, explicitly increment its reference count with `usb_get_dev(udev)` when storing it in the driver's private data. Correspondingly, decrement the reference count with `usb_put_dev(data->udev)` in the `bfusb_disconnect()` callback.
This ensures `udev` remains valid while referenced by the driver's private data and is properly released when no longer needed.
How was this tested?
I'm not saying the change is wrong, just that I don't think it's actually a leak, or fix of anything real.
Or do you have a workload that shows this is needed? If so, what is the crash reported?
thanks,
greg k-h