This driver's probe() uses a mix of devm_ and non-devm_ functions. This
means that the remove order will not be the exact opposite of the probe
order.
Remove order:
1. remove() executes:
iio_device_unregister
iio_triggered_buffer_cleanup
iio_trigger_unregister
(A)
2. core frees devm resources in reverse order:
free_irq
iio_trigger_free
iio_device_free
In (A) the trigger has been unregistered, but the irq handler is still
registered and active, so the trigger may still be touched via
interrupt -> as3935_event_work. This is a potential use-after-unregister.
Given that the delayed work is never canceled explicitly, it may run even
after iio_device_free. This is a potential use-after-free.
Solution: convert all probe functions to their devm_ equivalents.
Add a devm callback, called by the core on remove right after irq_free,
which explicitly cancels the delayed work. This will guarantee that all
resources are freed in the correct order.
As an added bonus, some boilerplate code can be removed.
Signed-off-by: Sven Van Asbroeck <TheSven73@xxxxxxxxx>
---
drivers/iio/proximity/as3935.c | 49 ++++++++++++++--------------------
1 file changed, 20 insertions(+), 29 deletions(-)
diff --git a/drivers/iio/proximity/as3935.c b/drivers/iio/proximity/as3935.c
index f130388a16a0..6e366e772164 100644
--- a/drivers/iio/proximity/as3935.c
+++ b/drivers/iio/proximity/as3935.c
@@ -345,6 +345,14 @@ static SIMPLE_DEV_PM_OPS(as3935_pm_ops, as3935_suspend, as3935_resume);
#define AS3935_PM_OPS NULL
#endif
+static void as3935_stop_work(void *data)
+{
+ struct iio_dev *indio_dev = data;
+ struct as3935_state *st = iio_priv(indio_dev);
+
+ cancel_delayed_work_sync(&st->work);
+}
+
static int as3935_probe(struct spi_device *spi)
{
struct iio_dev *indio_dev;
@@ -368,7 +376,6 @@ static int as3935_probe(struct spi_device *spi)
spi_set_drvdata(spi, indio_dev);
mutex_init(&st->lock);
- INIT_DELAYED_WORK(&st->work, as3935_event_work);
ret = of_property_read_u32(np,
"ams,tuning-capacitor-pf", &st->tune_cap);
@@ -414,22 +421,27 @@ static int as3935_probe(struct spi_device *spi)
iio_trigger_set_drvdata(trig, indio_dev);
trig->ops = &iio_interrupt_trigger_ops;
- ret = iio_trigger_register(trig);
+ ret = devm_iio_trigger_register(&spi->dev, trig);
if (ret) {
dev_err(&spi->dev, "failed to register trigger\n");
return ret;
}
- ret = iio_triggered_buffer_setup(indio_dev, iio_pollfunc_store_time,
- &as3935_trigger_handler, NULL);
+ ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
+ iio_pollfunc_store_time, as3935_trigger_handler, NULL);
if (ret) {
dev_err(&spi->dev, "cannot setup iio trigger\n");
- goto unregister_trigger;
+ return ret;
}
calibrate_as3935(st);
+ INIT_DELAYED_WORK(&st->work, as3935_event_work);
+ ret = devm_add_action(&spi->dev, as3935_stop_work, indio_dev);
+ if (ret)
+ return ret;
+
ret = devm_request_irq(&spi->dev, spi->irq,
&as3935_interrupt_handler,
IRQF_TRIGGER_RISING,
@@ -438,35 +450,15 @@ static int as3935_probe(struct spi_device *spi)
if (ret) {
dev_err(&spi->dev, "unable to request irq\n");
- goto unregister_buffer;
+ return ret;
}
- ret = iio_device_register(indio_dev);
+ ret = devm_iio_device_register(&spi->dev, indio_dev);
if (ret < 0) {
dev_err(&spi->dev, "unable to register device\n");
- goto unregister_buffer;
+ return ret;
}
return 0;
-
-unregister_buffer:
- iio_triggered_buffer_cleanup(indio_dev);
-
-unregister_trigger:
- iio_trigger_unregister(st->trig);
-
- return ret;
-}
-
-static int as3935_remove(struct spi_device *spi)
-{
- struct iio_dev *indio_dev = spi_get_drvdata(spi);
- struct as3935_state *st = iio_priv(indio_dev);
-
- iio_device_unregister(indio_dev);
- iio_triggered_buffer_cleanup(indio_dev);
- iio_trigger_unregister(st->trig);
-
- return 0;
}
static const struct of_device_id as3935_of_match[] = {
@@ -488,7 +480,6 @@ static struct spi_driver as3935_driver = {
.pm = AS3935_PM_OPS,
},
.probe = as3935_probe,
- .remove = as3935_remove,
.id_table = as3935_id,
};
module_spi_driver(as3935_driver);
--
2.17.1
