Re: [PATCH] iio: chemical: atlas-sensor: use iio_trigger_poll_nested() to fix remove UAF

On Monday, 3 August 2026 at 02:32, Jonathan Cameron <[email protected]> wrote:

> On Sun,  2 Aug 2026 07:18:58 +0000
> Fan Wu <[email protected]> wrote:
> 
> > The atlas driver requests its hardware data-ready IRQ with
> > devm_request_threaded_irq(); its threaded handler queues an irq_work,
> > atlas_work_handler(), that calls iio_trigger_poll(data->trig).
> >
> > The IRQ is devm-managed, so free_irq() runs from the devres unwind after
> > atlas_remove() returns without flushing that irq_work.  Once a buffer is
> > enabled, conversion-complete IRQs keep firing and queueing it; a pending
> > irq_work can therefore run after the unwind has freed atlas_data/indio_dev
> > and the trigger, when atlas_work_handler() derives the atlas_data pointer
> > via container_of() and dereferences data->trig, a use-after-free.
> >
> > Call iio_trigger_poll_nested() directly from the threaded handler instead
> > of bouncing through irq_work.  free_irq() then drains the threaded handler,
> > closing the window; other iio drivers with a threaded data-ready IRQ do the
> > same (e.g. bmi270).
> >
> > This issue was found by an in-house static analysis tool.
> >
> > Fixes: 7103b99b031c ("iio: chemical: atlas-ph-sensor: reorg driver to allow multiple chips")
> > Cc: [email protected] # v6.4+
> > Assisted-by: Codex:gpt-5.6
> > Signed-off-by: Fan Wu <[email protected]>
> 
> Added another email address for Matt.
> 
> There are reasons why he might have got the irq_work route but I can't
> recall if they applied.  What we lose here is the ability to hang
> other consumers that need a top half of the trigger.  If that doesn't
> matter then agreed your solution is the cleanest path forwards.

Hello all! Looking at the 'git log' and 10 years ago so it I'm only doing conjecture on what I was probably thinking back in 2016.
If I recall the reasoning was to allow other consumer iio triggers (e.g. hrtimer timer or sysfs)
to map to the atlas sensors.

Thanks,

Matt

> 
> One day someone will get the time to make combining nested
> trigger handling with top halves cleverer than current approach of
> just not running them.
> 
> Jonathan
> 
> 
> > ---
> >
> >  drivers/iio/chemical/atlas-sensor.c | 13 +------------
> >  1 file changed, 1 insertion(+), 12 deletions(-)
> >
> > diff --git a/drivers/iio/chemical/atlas-sensor.c b/drivers/iio/chemical/atlas-sensor.c
> > --- a/drivers/iio/chemical/atlas-sensor.c
> > +++ b/drivers/iio/chemical/atlas-sensor.c
> > @@ -13,7 +13,6 @@
> >  #include <linux/mutex.h>
> >  #include <linux/err.h>
> >  #include <linux/irq.h>
> > -#include <linux/irq_work.h>
> >  #include <linux/i2c.h>
> >  #include <linux/mod_devicetable.h>
> >  #include <linux/regmap.h>
> > @@ -88,7 +87,6 @@ struct atlas_data {
> >  	struct iio_trigger *trig;
> >  	const struct atlas_device *chip;
> >  	struct regmap *regmap;
> > -	struct irq_work work;
> >  	unsigned int interrupt_enabled;
> >  	/* 96-bit data + 32-bit pad + 64-bit timestamp */
> >  	__be32 buffer[6] __aligned(8);
> > @@ -437,13 +435,6 @@ static const struct iio_buffer_setup_ops atlas_buffer_setup_ops = {
> >  	.predisable = atlas_buffer_predisable,
> >  };
> >
> > -static void atlas_work_handler(struct irq_work *work)
> > -{
> > -	struct atlas_data *data = container_of(work, struct atlas_data, work);
> > -
> > -	iio_trigger_poll(data->trig);
> > -}
> > -
> >  static irqreturn_t atlas_trigger_handler(int irq, void *private)
> >  {
> >  	struct iio_poll_func *pf = private;
> > @@ -470,7 +461,7 @@ static irqreturn_t atlas_interrupt_handler(int irq, void *private)
> >  	struct iio_dev *indio_dev = private;
> >  	struct atlas_data *data = iio_priv(indio_dev);
> >
> > -	irq_work_queue(&data->work);
> > +	iio_trigger_poll_nested(data->trig);
> >
> >  	return IRQ_HANDLED;
> >  }
> > @@ -666,8 +657,6 @@ static int atlas_probe(struct i2c_client *client)
> >  		goto unregister_trigger;
> >  	}
> >
> > -	init_irq_work(&data->work, atlas_work_handler);
> > -
> >  	if (client->irq > 0) {
> >  		/* interrupt pin toggles on new conversion */
> >  		ret = devm_request_threaded_irq(&client->dev, client->irq,
> > --
> > 2.43.0
> >
> >
> 
>