From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.19.201]:54868 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752069AbaG0QkC (ORCPT ); Sun, 27 Jul 2014 12:40:02 -0400 Message-ID: <53D52BF3.6020903@kernel.org> Date: Sun, 27 Jul 2014 17:42:27 +0100 From: Jonathan Cameron MIME-Version: 1.0 To: Martin Fuzzey , linux-iio@vger.kernel.org Subject: Re: [PATCH] iio: core: Fix double free. References: <20140721132215.11583.81979.stgit@localhost> In-Reply-To: <20140721132215.11583.81979.stgit@localhost> Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org On 21/07/14 14:22, Martin Fuzzey wrote: > When an error occured during event registration memory was freed twice > resulting in kernel memory corruption and a crash in unrelated code. > > The problem was caused by > iio_device_unregister_eventset() > iio_device_unregister_sysfs() > > being called twice, once on the error path and then > again via iio_dev_release(). > > Fix this by making these two functions idempotent so they > may be called multiple times. > > The problem was observed before applying > 78b33216 iio:core: Handle error when mask type is not separate > > Signed-off-by: Martin Fuzzey Good catch. Applied to the fixes-togreg branch of iio.git and marked for stable. Given the timing this might end up waiting until after the upcoming merge windows closes. It's been there a long time with you being the first to notice so I'm not that fussed about rushing it out and annoying Linus! Jonathan > --- > drivers/iio/industrialio-core.c | 5 +++-- > drivers/iio/industrialio-event.c | 1 + > 2 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c > index 4b1f375..fa06197 100644 > --- a/drivers/iio/industrialio-core.c > +++ b/drivers/iio/industrialio-core.c > @@ -828,8 +828,7 @@ static int iio_device_add_channel_sysfs(struct iio_dev *indio_dev, > * @attr_list: List of IIO device attributes > * > * This function frees the memory allocated for each of the IIO device > - * attributes in the list. Note: if you want to reuse the list after calling > - * this function you have to reinitialize it using INIT_LIST_HEAD(). > + * attributes in the list. > */ > void iio_free_chan_devattr_list(struct list_head *attr_list) > { > @@ -837,6 +836,7 @@ void iio_free_chan_devattr_list(struct list_head *attr_list) > > list_for_each_entry_safe(p, n, attr_list, l) { > kfree(p->dev_attr.attr.name); > + list_del(&p->l); > kfree(p); > } > } > @@ -917,6 +917,7 @@ static void iio_device_unregister_sysfs(struct iio_dev *indio_dev) > > iio_free_chan_devattr_list(&indio_dev->channel_attr_list); > kfree(indio_dev->chan_attr_group.attrs); > + indio_dev->chan_attr_group.attrs = NULL; > } > > static void iio_dev_release(struct device *device) > diff --git a/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-event.c > index bfbf4d4..ad7a35f 100644 > --- a/drivers/iio/industrialio-event.c > +++ b/drivers/iio/industrialio-event.c > @@ -492,6 +492,7 @@ int iio_device_register_eventset(struct iio_dev *indio_dev) > error_free_setup_event_lines: > iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list); > kfree(indio_dev->event_interface); > + indio_dev->event_interface = NULL; > return ret; > } > >