[PATCH] iio: trigger: sysfs: fix use-after-free on remove

[PATCH] iio: trigger: sysfs: fix use-after-free on remove

[Vincent Whitchurch]

Ensure that the irq_work has completed before the trigger is freed.

 ==================================================================
 BUG: KASAN: use-after-free in irq_work_run_list
 Read of size 8 at addr 0000000064702248 by task python3/25

 Call Trace:
  irq_work_run_list
  irq_work_tick
  update_process_times
  tick_sched_handle
  tick_sched_timer
  __hrtimer_run_queues
  hrtimer_interrupt

 Allocated by task 25:
  kmem_cache_alloc_trace
  iio_sysfs_trig_add
  dev_attr_store
  sysfs_kf_write
  kernfs_fop_write_iter
  new_sync_write
  vfs_write
  ksys_write
  sys_write

 Freed by task 25:
  kfree
  iio_sysfs_trig_remove
  dev_attr_store
  sysfs_kf_write
  kernfs_fop_write_iter
  new_sync_write
  vfs_write
  ksys_write
  sys_write

 ==================================================================

Fixes: e64e7d5c8c86e ("iio:trigger:sysfs Move out of staging.")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
---
 drivers/iio/trigger/iio-trig-sysfs.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/iio/trigger/iio-trig-sysfs.c b/drivers/iio/trigger/iio-trig-sysfs.c
index 2a4b75897910..3d911c24b265 100644
--- a/drivers/iio/trigger/iio-trig-sysfs.c
+++ b/drivers/iio/trigger/iio-trig-sysfs.c
@@ -191,6 +191,7 @@ static int iio_sysfs_trigger_remove(int id)
 	}
 
 	iio_trigger_unregister(t->trig);
+	irq_work_sync(&t->work);
 	iio_trigger_free(t->trig);
 
 	list_del(&t->l);
-- 
2.34.1

Re: [PATCH] iio: trigger: sysfs: fix use-after-free on remove

[Lars-Peter Clausen]

On 5/19/22 11:19, Vincent Whitchurch wrote:
> [...]
>   
>
> Fixes: e64e7d5c8c86e ("iio:trigger:sysfs Move out of staging.")
> Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>

Thanks for the patch!

Strictly speaking the Fixes: should be

f38bc926d022 ("staging:iio:sysfs-trigger: Use irq_work to properly 
active trigger")


Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>

> ---
>   drivers/iio/trigger/iio-trig-sysfs.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/iio/trigger/iio-trig-sysfs.c b/drivers/iio/trigger/iio-trig-sysfs.c
> index 2a4b75897910..3d911c24b265 100644
> --- a/drivers/iio/trigger/iio-trig-sysfs.c
> +++ b/drivers/iio/trigger/iio-trig-sysfs.c
> @@ -191,6 +191,7 @@ static int iio_sysfs_trigger_remove(int id)
>   	}
>   
>   	iio_trigger_unregister(t->trig);
> +	irq_work_sync(&t->work);
>   	iio_trigger_free(t->trig);
>   
>   	list_del(&t->l);

Re: [PATCH] iio: trigger: sysfs: fix use-after-free on remove

[Jonathan Cameron]

On Thu, 19 May 2022 11:58:03 +0200
Lars-Peter Clausen <lars@metafoo.de> wrote:

> On 5/19/22 11:19, Vincent Whitchurch wrote:
> > [...]
> >   
> >
> > Fixes: e64e7d5c8c86e ("iio:trigger:sysfs Move out of staging.")
> > Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>  
> 
> Thanks for the patch!
> 
> Strictly speaking the Fixes: should be
> 
> f38bc926d022 ("staging:iio:sysfs-trigger: Use irq_work to properly 
> active trigger")
> 
> 
> Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
I've changed the fixes tag and applied to the fixes-togreg branch of iio.git.

Thanks,

Jonathan

> 
> > ---
> >   drivers/iio/trigger/iio-trig-sysfs.c | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/iio/trigger/iio-trig-sysfs.c b/drivers/iio/trigger/iio-trig-sysfs.c
> > index 2a4b75897910..3d911c24b265 100644
> > --- a/drivers/iio/trigger/iio-trig-sysfs.c
> > +++ b/drivers/iio/trigger/iio-trig-sysfs.c
> > @@ -191,6 +191,7 @@ static int iio_sysfs_trigger_remove(int id)
> >   	}
> >   
> >   	iio_trigger_unregister(t->trig);
> > +	irq_work_sync(&t->work);
> >   	iio_trigger_free(t->trig);
> >   
> >   	list_del(&t->l);  
> 
>