From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: Help with confirming an error trace in drivers/input/touchscreen/ad7879-spi.c Date: Thu, 16 Feb 2017 15:31:36 -0800 Message-ID: <20170216233136.GA6708@dtor-ws> References: <7a8799eb4ddca5b4b52991158f8ddc87@cs.utah.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pf0-f195.google.com ([209.85.192.195]:32850 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933695AbdBPXbk (ORCPT ); Thu, 16 Feb 2017 18:31:40 -0500 Received: by mail-pf0-f195.google.com with SMTP id e4so2600466pfg.0 for ; Thu, 16 Feb 2017 15:31:39 -0800 (PST) Content-Disposition: inline In-Reply-To: <7a8799eb4ddca5b4b52991158f8ddc87@cs.utah.edu> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Shaobo Cc: linux-input@vger.kernel.org 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