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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: Martin Fuzzey <mfuzzey@parkeon.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
hifive-unleashed-5.1
Martin Fuzzey 2015-02-19 15:17:44 +01:00 committed by Jonathan Cameron
parent af5e1a6831
commit c1b03ab5e8
2 changed files with 4 additions and 2 deletions
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5
drivers/iio/industrialio-core.c
View File

@ -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)

1
drivers/iio/industrialio-event.c
View File

@ -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;
}