Re: Help with confirming an error trace in drivers/input/touchscreen/ad7879-spi.c

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi Shaobo,

On Thu, Feb 16, 2017 at 04:27:00PM -0700, Shaobo wrote:
> Hi there,
> 
> My name is Shaobo He and I am a graduate student at University of
> Utah. I am applying a static analysis tool to the Linux device
> drivers and got an error trace of null pointer dereference in
> drivers/input/touchscreen/ad7879-spi.c staring from
> `ad7879_spi_multi_read`: it calls `ad7879_spi_xfer` with the
> argument `tx_buf` being NULL, which gets dereferenced at line 52
> given the argument `count` being 1. As you can see, the error trace
> is only plausible since it depends on certain conditions. To be more
> specific, is it possible for the count argument to be 1. Therefore,
> I was wondering if you could help me confirm it since you are one of
> the authors of this driver.
> 
> Thanks for your time. I am looking forward to your reply.

We never call ad7879_spi_multi_read() with count == 1, so this scenario
is not going to happen. Given that this is driiver-private code and not
a public API I think it is OK-ish.

Thanks.

-- 
Dmitry