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>
c1b03ab5e8