Re: [PATCH] rust: serdev: Fix race condition on driver probe fail

[Gary Guo]

On Sat Sep 5, 2026 at 1:22 AM BST, Markus Probst wrote:
> On Fri, 2026-09-04 at 23:54 +0000, Markus Probst wrote:
>> If `Driver::probe` fails, the pointer to the driver data (`PrivateData`)
>> will first be set to NULL by `drvdata_obtain` and only after that the
>> serdev device will be closed by Drop. Thus there is a small window in
>> which the serdev device is still open, but the pointer to the driver data
>> is NULL. Therefore it is possible that `receive_buf_callback` might try to
>> access the `active` mutex on a null pointer.
> It seems, Sashiko found the same issue in a different unrelated place
> too (while reviewing this patch):
>
> https://sashiko.dev/#/patchset/20260905-rust_serdev_fix-v1-1-2ea92b154a6b%40posteo.de
>
> Unfortunately, I cannot fix this one so easily, because the serdev
> device needs to be open for the entire lifetime of the "real" driver
> data (Driver::Data).

What would go wrong if the device is closed before destroying the driver data?

Best,
Gary