Re: [PATCH v4 01/11] media: cadence: csi2rx: Unregister v4l2 async notifier

[Pratyush Yadav]

On 07/10/21 02:31AM, Laurent Pinchart wrote:
> Hi Pratyush,
> 
> Thank you for the patch.
> 
> On Wed, Sep 15, 2021 at 05:32:30PM +0530, Pratyush Yadav wrote:
> > The notifier is added to the global notifier list when registered. When
> > the module is removed, the struct csi2rx_priv in which the notifier is
> > embedded, is destroyed. As a result the notifier list has a reference to
> > a notifier that no longer exists. This causes invalid memory accesses
> > when the list is iterated over. Similar for when the probe fails.
> > 
> > Unregister and clean up the notifier to avoid this.
> > 
> > Fixes: 1fc3b37f34f6 ("media: v4l: cadence: Add Cadence MIPI-CSI2 RX driver")
> > Signed-off-by: Pratyush Yadav <p.yadav@xxxxxx>
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> 
> Note that there are other issues in the driver in cleanup paths, in
> particular a missing v4l2_async_notifier_cleanup() call in
> csi2rx_parse_dt() when v4l2_async_notifier_add_fwnode_remote_subdev()
> fails (moving the one from the other error path to an err label would be
> best), and missing media_entity_cleanup() calls in both the probe error
> path and the remove handler. Would you like to submit fixes for those ?

Sure, will do.

> 
> > ---
> > 
> > (no changes since v3)
> > 
> > Changes in v3:
> > - New in v3.
> > 
> >  drivers/media/platform/cadence/cdns-csi2rx.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/drivers/media/platform/cadence/cdns-csi2rx.c b/drivers/media/platform/cadence/cdns-csi2rx.c
> > index 7b44ab2b8c9a..d60975f905d6 100644
> > --- a/drivers/media/platform/cadence/cdns-csi2rx.c
> > +++ b/drivers/media/platform/cadence/cdns-csi2rx.c
> > @@ -469,6 +469,7 @@ static int csi2rx_probe(struct platform_device *pdev)
> >  	return 0;
> >  
> >  err_cleanup:
> > +	v4l2_async_nf_unregister(&csi2rx->notifier);
> >  	v4l2_async_nf_cleanup(&csi2rx->notifier);
> >  err_free_priv:
> >  	kfree(csi2rx);
> > @@ -479,6 +480,8 @@ static int csi2rx_remove(struct platform_device *pdev)
> >  {
> >  	struct csi2rx_priv *csi2rx = platform_get_drvdata(pdev);
> >  
> > +	v4l2_async_nf_unregister(&csi2rx->notifier);
> > +	v4l2_async_nf_cleanup(&csi2rx->notifier);
> >  	v4l2_async_unregister_subdev(&csi2rx->subdev);
> >  	kfree(csi2rx);
> >  
> 
> -- 
> Regards,
> 
> Laurent Pinchart

-- 
Regards,
Pratyush Yadav
Texas Instruments Inc.