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Commit c1b03ab5 authored by Martin Fuzzey's avatar Martin Fuzzey Committed by Jonathan Cameron
Browse files

iio: core: Fix double free. 



When an error occurred 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: default avatarMartin Fuzzey <mfuzzey@parkeon.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent af5e1a68

drivers/iio/industrialio-core.c

+3 −2
Original line number Diff line number Diff line
@@ -847,8 +847,7 @@ 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)

{
@@ -856,6 +855,7 @@ 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);

	}

}
@@ -936,6 +936,7 @@ 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)

drivers/iio/industrialio-event.c

+1 −0
Original line number Diff line number Diff line
@@ -500,6 +500,7 @@ 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;

}