From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from saturn.retrosnub.co.uk ([178.18.118.26]:60696 "EHLO saturn.retrosnub.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755262AbaCOQXn (ORCPT ); Sat, 15 Mar 2014 12:23:43 -0400 Message-ID: <53247EC9.6090505@kernel.org> Date: Sat, 15 Mar 2014 16:24:41 +0000 From: Jonathan Cameron MIME-Version: 1.0 To: Krzysztof Kozlowski , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org CC: Beomho Seo , Lars-Peter Clausen Subject: Re: [PATCH] iio: cm36651: Fix i2c client leak and possible NULL pointer dereference References: <1394098390-11213-1-git-send-email-k.kozlowski@samsung.com> In-Reply-To: <1394098390-11213-1-git-send-email-k.kozlowski@samsung.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org On 06/03/14 09:33, Krzysztof Kozlowski wrote: > During probe the driver allocates dummy I2C devices (i2c_new_dummy()) > but they aren't unregistered during driver remove or probe failure. > > Additionally driver does not check the return value of i2c_new_dummy(). > In case of error (i2c_new_device(): memory allocation failure or I2C > address cannot be used) this function returns NULL which is later > dereferenced by i2c_smbus_{read,write}_data() functions. > > Fix issues by properly checking for i2c_new_dummy() return value and > unregistering I2C devices on driver remove or probe failure. > > Signed-off-by: Krzysztof Kozlowski Good catch, but the error path needs more care. > --- > drivers/iio/light/cm36651.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/iio/light/cm36651.c b/drivers/iio/light/cm36651.c > index a45e07492db3..e7e9a597159f 100644 > --- a/drivers/iio/light/cm36651.c > +++ b/drivers/iio/light/cm36651.c > @@ -653,6 +653,11 @@ static int cm36651_probe(struct i2c_client *client, > cm36651->ps_client = i2c_new_dummy(client->adapter, > CM36651_I2C_ADDR_PS); > cm36651->ara_client = i2c_new_dummy(client->adapter, CM36651_ARA); > + if (!cm36651->ps_client || !cm36651->ara_client) { > + dev_err(&client->dev, "%s: new i2c device failed\n", __func__); > + ret = -ENODEV; > + goto error_i2c_unregister; > + } The two failures need to be handled independently as we only want to unregister those that succeeded. i2c_new_dummy will not return an error and leave a device registered. This is particularly true given the first thing that i2c_unregister_device does is to derefence the client pointer. That will cause a segfault if you do it for NULL as here. > mutex_init(&cm36651->lock); > indio_dev->dev.parent = &client->dev; > indio_dev->channels = cm36651_channels; > @@ -687,6 +692,11 @@ error_free_irq: > free_irq(client->irq, indio_dev); > error_disable_reg: > regulator_disable(cm36651->vled_reg); > +error_i2c_unregister: > + if (cm36651->ps_client) > + i2c_unregister_device(cm36651->ps_client); > + if (cm36651->ara_client) > + i2c_unregister_device(cm36651->ara_client); > return ret; > } > > @@ -698,6 +708,8 @@ static int cm36651_remove(struct i2c_client *client) > iio_device_unregister(indio_dev); > regulator_disable(cm36651->vled_reg); > free_irq(client->irq, indio_dev); > + i2c_unregister_device(cm36651->ps_client); > + i2c_unregister_device(cm36651->ara_client); Good catch. > > return 0; > } >