Messages in this thread |  | | Date | Wed, 6 May 2026 18:37:22 +0100 | | From | Jonathan Cameron <> | | Subject | Re: [PATCH] iio: gyro: itg3200: fix i2c read into the wrong stack location |
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On Wed, 6 May 2026 08:08:24 +0100 David CARLIER <devnexen@gmail.com> wrote:
> On Wed, 6 May 2026 at 07:40, Andy Shevchenko > <andriy.shevchenko@intel.com> 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@intel.com> > > > > -- > > 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 !
I was assuming the fixes tag was wrong and this was a result of rework, but you are correct it goes all they way back! Huh. I guess last minute driver changes that didn't quite get tested and clearly not a heavily used device! 13 years of not working.
We could drop the driver, but it's possible it is in use just not with buffered support (which is a separate CONFIG option) Also drops don't get backported so we'd be leaving it broken and stale. So let's fix it now and consider a drop later.
Applied to the fixes-togreg branch of iio.git
Thanks, Jonathan
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