On 19/02/15 14:17, Martin Fuzzey wrote:
> 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@xxxxxxxxxxx>
Good find. I'm trying to get my head around why those functions are
in the release rather than the unregister. Need to think on this
a little more to work out if this is the right fix or is papering
over a nastier issue.
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 af3e76d..f009d05 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -832,8 +832,7 @@ 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)
> {
> @@ -841,6 +840,7 @@ 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);
> }
> }
> @@ -921,6 +921,7 @@ 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 0c1e37e..35c02ae 100644
> --- a/drivers/iio/industrialio-event.c
> +++ b/drivers/iio/industrialio-event.c
> @@ -493,6 +493,7 @@ 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;
> }
>
>
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