Re: [PATCH] iio: gyro: itg3200: fix i2c read into the wrong stack location

[David CARLIER]

On Wed, 6 May 2026 at 07:40, Andy Shevchenko
<andriy.shevchenko@xxxxxxxxx> wrote:
>
> On Tue, May 05, 2026 at 02:37:48PM +0100, David Carlier wrote:
> > itg3200_read_all_channels() takes `__be16 *buf' as a parameter and
> > fills the i2c_msg destination as `(char *)&buf'. Since `buf' is the
> > parameter (a pointer), `&buf' is the address of the local pointer
> > slot on the stack of itg3200_read_all_channels(), not the address
> > of the caller's scan buffer. The (char *) cast hides the type
> > mismatch.
> >
> > i2c_transfer() therefore writes ITG3200_SCAN_ELEMENTS * sizeof(s16)
> > = 8 bytes into the parameter's stack slot, which is discarded when
> > the function returns. The caller's scan buffer in
> > itg3200_trigger_handler() is never written to, so
> > iio_push_to_buffers_with_timestamp() pushes uninitialised stack
> > contents to userspace via /dev/iio:deviceX every scan -- both a
> > functional bug (no actual gyroscope or temperature data is
> > delivered through the triggered buffer) and an information leak.
> >
> > The non-buffered read_raw() path is unaffected: it goes through
> > itg3200_read_reg_s16() which uses `&out' on a local s16 value,
> > where that is correct.
> >
> > Drop the spurious `&' so the i2c read writes into the caller's
> > buffer.
>
> Very good catch! I'm puzzled if that code was ever tested. Do you have an HW
> and that's how you enter to this bug?
>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxx>
>
> --
> With Best Regards,
> Andy Shevchenko
>
>

Thanks! No HW on my side -- found by inspection. I had recently looked
  at a similar `(char *)&buf' / `(char *)buf' mix-up in another
driver,
  so I went grepping for the same shape and itg3200 stood out. For
  contrast, drivers/iio/humidity/hdc3020.c::hdc3020_read_bytes() has
the
  same signature (u8 *buf parameter) and assigns `.buf = buf'
correctly.

  Compile-tested only; the analysis in the changelog is what I'm
relying
  on.

Cheers !