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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Dmitry Rokosov <ddrokosov@sberdevices.ru>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Stable@vger.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>
Subject: [PATCH 4.19 24/49] iio:chemical:ccs811: rearrange iio trigger get and register
Date:   Thu, 30 Jun 2022 15:46:37 +0200
Message-Id: <20220630133234.612211320@linuxfoundation.org>
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From: Dmitry Rokosov <DDRokosov@sberdevices.ru>

commit d710359c0b445e8c03e24f19ae2fb79ce7282260 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: f1f065d7ac30 ("iio: chemical: ccs811: Add support for data ready trigger")
Signed-off-by: Dmitry Rokosov <ddrokosov@sberdevices.ru>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220524181150.9240-5-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>
---
 drivers/iio/chemical/ccs811.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/iio/chemical/ccs811.c
+++ b/drivers/iio/chemical/ccs811.c
@@ -421,11 +421,11 @@ static int ccs811_probe(struct i2c_clien
 		data->drdy_trig->dev.parent = &client->dev;
 		data->drdy_trig->ops = &ccs811_trigger_ops;
 		iio_trigger_set_drvdata(data->drdy_trig, indio_dev);
-		indio_dev->trig = data->drdy_trig;
-		iio_trigger_get(indio_dev->trig);
 		ret = iio_trigger_register(data->drdy_trig);
 		if (ret)
 			goto err_poweroff;
+
+		indio_dev->trig = iio_trigger_get(data->drdy_trig);
 	}
 
 	ret = iio_triggered_buffer_setup(indio_dev, NULL,