iio:humidity:hts221: rearrange iio trigger get and register

BugLink: https://bugs.launchpad.net/bugs/1986718
commit 10b9c2c33ac706face458feab8965f11743c98c0 upstream.

IIO trigger interface function iio_trigger_get() should be called after
iio_trigger_register() (or its devm analogue) strictly, because of
iio_trigger_get() acquires module refcnt based on the trigger->owner
pointer, which is initialized inside iio_trigger_register() to
THIS_MODULE.
If this call order is wrong, the next iio_trigger_put() (from sysfs
callback or "delete module" path) will dereference "default" module
refcnt, which is incorrect behaviour.

Fixes: e4a70e3e7d84 ("iio: humidity: add support to hts221 rh/temp combo device")
Signed-off-by: Dmitry Rokosov <ddrokosov@sberdevices.ru>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220524181150.9240-6-ddrokosov@sberdevices.ru
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/drivers/iio/humidity/hts221_buffer.c b/drivers/iio/humidity/hts221_buffer.c
index f29692b9d2db0e39704991dcdcff07bae184fb25..66b32413cf5e26a62a2464374df8cb56da02dfcc 100644 (file)
--- a/drivers/iio/humidity/hts221_buffer.c
+++ b/drivers/iio/humidity/hts221_buffer.c
@@ -135,9 +135,12 @@ int hts221_allocate_trigger(struct iio_dev *iio_dev)
 
        iio_trigger_set_drvdata(hw->trig, iio_dev);
        hw->trig->ops = &hts221_trigger_ops;
+
+       err = devm_iio_trigger_register(hw->dev, hw->trig);
+
        iio_dev->trig = iio_trigger_get(hw->trig);
 
-       return devm_iio_trigger_register(hw->dev, hw->trig);
+       return err;
 }
 
 static int hts221_buffer_preenable(struct iio_dev *iio_dev)