Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Thu, 9 Apr 2020 13:36:01 -0700
From:   Dmitry Torokhov <dmitry.torokhov@gmail.com>
To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc:     Oliver Graute <oliver.graute@gmail.com>,
        Marco Felsch <m.felsch@pengutronix.de>,
        Oliver Graute <oliver.graute@kococonnector.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Sasha Levin <sashal@kernel.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        linux-input@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1] Input: edt-ft5x06 - fix crash on EDT EP0110M09
Message-ID: <20200409203601.GQ75430@dtor-ws>
References: <1586424425-27038-1-git-send-email-oliver.graute@gmail.com>
 <20200409105253.qvezbikpbnrkig52@pengutronix.de>
 <20200409120242.GA17410@portage>
 <20200409123622.GA3676135@smile.fi.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20200409123622.GA3676135@smile.fi.intel.com>
User-Agent: Mutt/1.12.2 (2019-09-21)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, Apr 09, 2020 at 03:36:22PM +0300, Andy Shevchenko wrote:
> On Thu, Apr 09, 2020 at 02:02:42PM +0200, Oliver Graute wrote:
> > On 09/04/20, Marco Felsch wrote:
> > > Hi Oliver,
> > > 
> > > thanks for your patch.
> > > 
> > > On 20-04-09 11:27, Oliver Graute wrote:
> > > > From: Oliver Graute <oliver.graute@kococonnector.com>
> > > 
> > > ...
> > > 
> > > >  drivers/input/touchscreen/edt-ft5x06.c | 4 ----
> > > >  1 file changed, 4 deletions(-)
> > > > 
> > > > diff --git a/drivers/input/touchscreen/edt-ft5x06.c b/drivers/input/touchscreen/edt-ft5x06.c
> > > > index 06aa8ba0b6d7..6fbc87d041a1 100644
> > > > --- a/drivers/input/touchscreen/edt-ft5x06.c
> > > > +++ b/drivers/input/touchscreen/edt-ft5x06.c
> > > > @@ -819,10 +819,6 @@ static int edt_ft5x06_ts_identify(struct i2c_client *client,
> > > >  	 * to have garbage in there
> > > >  	 */
> > > >  	memset(rdbuf, 0, sizeof(rdbuf));
> > > > -	error = edt_ft5x06_ts_readwrite(client, 1, "\xBB",
> > > > -					EDT_NAME_LEN - 1, rdbuf);
> > > > -	if (error)
> > > > -		return error;
> > > 
> > > 
> > > I don't see how this call can corrupt the stack..
> > 
> > I admit that this is strange. The patch fixed my problems so I posted
> > it. Still interested in the root-cause.
> 
> I'm wondering how you nailed down to this function? Have you able to use kASAN?
> 
> By the way, what I?C controller behind this? Maybe the bug in its driver?

I would try instrumenting drivers/i2c/busses/i2c-imx-lpi2c.c to make
sure it does not try to stuff into the rdbuf more data than requested...

Thanks.

-- 
Dmitry