On Tue, Jul 18, 2023 at 05:29:17PM +0200, Milan Zamazal wrote:
> Commit 813665564b3d ("iio: core: Convert to use firmware node handle
> instead of OF node") switched the kind of nodes to use for label
> retrieval in device registration. Probably an unwanted change in that
> commit was that if the device has no parent then NULL pointer is
> accessed. This is what happens in the stock IIO dummy driver when a
> new entry is created in configfs:
> # mkdir /sys/kernel/config/iio/devices/dummy/foo
> BUG: kernel NULL pointer dereference, address: ...
> ...
> Call Trace:
> ...
> asm_exc_page_fault
> container_offline
> __iio_device_register
> krealloc
> iio_device_attach_buffer
> iio_simple_dummy_configure_buffer
> iio_triggered_buffer_setup_ext
> iio_dummy_probe
> iio_sw_device_create
> device_make_group
> configfs_mkdir
Please, remove more unrelated lines in this backtrace. Ideally it should come
to ~4-5. For example, you posted a command line, it's obvious that you run
configfs, so the last (two) line(s) of the backtrace are redundant.
Then drop basic stuff, like:
asm_exc_page_fault
container_offline
krealloc
Then remove unrelated IIO internals.
> Since there seems to be no reason to make a parent device of an IIO
> dummy device mandatory, let’s prevent the invalid memory access in
> __iio_device_register when the parent device is NULL. With this
> change, the IIO dummy driver works fine with configfs.
The code wise it's okay now, so after addressing above
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
--
With Best Regards,
Andy Shevchenko
