Re: [PATCH 4.4 13/56] iio: trigger: free trigger resource correctly

[Ben Hutchings]

On Mon, 2017-11-13 at 13:55 +0100, Greg Kroah-Hartman wrote:
> 4.4-stable review patch.ÂÂIf anyone has any objections, please let me
> know.
> 
> ------------------
> 
> From: Alison Schofield <amsfield22@xxxxxxxxx>
> 
> 
> [ Upstream commit 10e840dfb0b7fc345082dd9e5fff3c1c02e7690e ]
> 
> These stand-alone trigger drivers were using iio_trigger_put()
> where they should have been using iio_trigger_free().ÂÂThe
> iio_trigger_put() adds a module_put which is bad since they
> never did a module_get.
> 
> In the sysfs driver, module_get/put's are used as triggers are
> added & removed. This extra module_put() occurs on an error path
> in the probe routine (probably rare).
> 
> In the bfin-timer & interrupt trigger drivers, the module resources
> are not explicitly managed, so it's doing a put on something that
> was never get'd.ÂÂIt occurs on the probe error path and on the
> remove path (not so rare).
> 
> Tested with the sysfs trigger driver.
> The bfin & interrupt drivers were build tested & inspected only.

In 4.4 the iio-trig-periodic-rtc seems to have the same bug (it has
been removed upstream).  Would it make sense to fix it in 4.4?

Ben.

> Signed-off-by: Alison Schofield <amsfield22@xxxxxxxxx>
> Signed-off-by: Jonathan Cameron <jic23@xxxxxxxxxx>
> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
> Âdrivers/iio/trigger/iio-trig-interrupt.cÂÂÂÂÂÂÂÂÂÂ|ÂÂÂÂ8 ++++----
> Âdrivers/iio/trigger/iio-trig-sysfs.cÂÂÂÂÂÂÂÂÂÂÂÂÂÂ|ÂÂÂÂ2 +-
> Âdrivers/staging/iio/trigger/iio-trig-bfin-timer.c |ÂÂÂÂ4 ++--
> Â3 files changed, 7 insertions(+), 7 deletions(-)
> 
> --- a/drivers/iio/trigger/iio-trig-interrupt.c
> +++ b/drivers/iio/trigger/iio-trig-interrupt.c
> @@ -58,7 +58,7 @@ static int iio_interrupt_trigger_probe(s
> Â	trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
> Â	if (!trig_info) {
> Â		ret = -ENOMEM;
> -		goto error_put_trigger;
> +		goto error_free_trigger;
> Â	}
> Â	iio_trigger_set_drvdata(trig, trig_info);
> Â	trig_info->irq = irq;
> @@ -83,8 +83,8 @@ error_release_irq:
> Â	free_irq(irq, trig);
> Âerror_free_trig_info:
> Â	kfree(trig_info);
> -error_put_trigger:
> -	iio_trigger_put(trig);
> +error_free_trigger:
> +	iio_trigger_free(trig);
> Âerror_ret:
> Â	return ret;
> Â}
> @@ -99,7 +99,7 @@ static int iio_interrupt_trigger_remove(
> Â	iio_trigger_unregister(trig);
> Â	free_irq(trig_info->irq, trig);
> Â	kfree(trig_info);
> -	iio_trigger_put(trig);
> +	iio_trigger_free(trig);
> Â
> Â	return 0;
> Â}
> --- a/drivers/iio/trigger/iio-trig-sysfs.c
> +++ b/drivers/iio/trigger/iio-trig-sysfs.c
> @@ -174,7 +174,7 @@ static int iio_sysfs_trigger_probe(int i
> Â	return 0;
> Â
> Âout2:
> -	iio_trigger_put(t->trig);
> +	iio_trigger_free(t->trig);
> Âfree_t:
> Â	kfree(t);
> Âout1:
> --- a/drivers/staging/iio/trigger/iio-trig-bfin-timer.c
> +++ b/drivers/staging/iio/trigger/iio-trig-bfin-timer.c
> @@ -259,7 +259,7 @@ out_free_irq:
> Âout1:
> Â	iio_trigger_unregister(st->trig);
> Âout:
> -	iio_trigger_put(st->trig);
> +	iio_trigger_free(st->trig);
> Â	return ret;
> Â}
> Â
> @@ -272,7 +272,7 @@ static int iio_bfin_tmr_trigger_remove(s
> Â		peripheral_free(st->t->pin);
> Â	free_irq(st->irq, st);
> Â	iio_trigger_unregister(st->trig);
> -	iio_trigger_put(st->trig);
> +	iio_trigger_free(st->trig);
> Â
> Â	return 0;
> Â}
> 
> 
> 
-- 
Ben Hutchings
Software Developer, Codethink Ltd.