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[89.64.59.228]) by smtp.gmail.com with ESMTPSA id m16sm1040421ljb.50.2019.03.11.11.01.09 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 11 Mar 2019 11:01:10 -0700 (PDT) Date: Mon, 11 Mar 2019 19:00:44 +0100 From: Tomasz Duszynski To: Sven Van Asbroeck Cc: Peter Rosin , Jonathan Cameron , Hartmut Knaack , Lars-Peter Clausen , Peter Meerwald-Stadler , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] iio: envelope-detector: fix use-after-free on device remove Message-ID: <20190311180042.GA17880@arch> References: <20190310193246.31761-1-TheSven73@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190310193246.31761-1-TheSven73@gmail.com> User-Agent: Mutt/1.11.3 (2019-02-01) Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org On Sun, Mar 10, 2019 at 03:32:46PM -0400, Sven Van Asbroeck wrote: > This driver's remove path never explicitly cancels the > delayed work. So it is possible for the delayed work to > run after the core has freed the private structure > (struct envelope). This is a potential use-after-free. > > Fix by adding a devm_add_action callback to the remove > path, called right after iio_device_unregister(), which > explicitly cancels the delayed work. > > This issue was detected with the help of Coccinelle. > > Signed-off-by: Sven Van Asbroeck > --- > drivers/iio/adc/envelope-detector.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/iio/adc/envelope-detector.c b/drivers/iio/adc/envelope-detector.c > index 2f2b563c1162..2f1c78b3ff44 100644 > --- a/drivers/iio/adc/envelope-detector.c > +++ b/drivers/iio/adc/envelope-detector.c > @@ -321,6 +321,14 @@ static const struct iio_info envelope_detector_info = { > .read_raw = &envelope_detector_read_raw, > }; > > +static void envelope_detector_stop_work(void *data) > +{ > + struct iio_dev *indio_dev = data; > + struct envelope *env = iio_priv(indio_dev); > + > + cancel_delayed_work_sync(&env->comp_timeout); > +} > + > static int envelope_detector_probe(struct platform_device *pdev) > { > struct device *dev = &pdev->dev; > @@ -395,6 +403,10 @@ static int envelope_detector_probe(struct platform_device *pdev) > return ret; > } > > + ret = devm_add_action(dev, envelope_detector_stop_work, indio_dev); > + if (ret) > + return ret; Just a random thought. Wouldn't devm_add_action_or_reset() be a better fit? In case adding action results in failure we will not get the chance to cancel work. > + > return devm_iio_device_register(dev, indio_dev); > } > > -- > 2.17.1 >