Re: [PATCH 2/3] drm/ingenic: Register devm action to cleanup encoders

[Paul Cercueil]

Hi Laurent,

Le lun. 18 janv. 2021 à 11:43, Laurent Pinchart 
<laurent.pinchart@xxxxxxxxxxxxxxxx> a écrit :
> Hi Paul,
>
> Thank you for the patch.
>
> On Sun, Jan 17, 2021 at 11:26:45AM +0000, Paul Cercueil wrote:
> >  Since the encoders have been devm-allocated, they will be freed way
> >  before drm_mode_config_cleanup() is called. To avoid use-after-free
> >  conditions, we then must ensure that drm_encoder_cleanup() is called
> >  before the encoders are freed.
>
> How about allocating the encoder with drmm_encoder_alloc() instead ?

That would work, but it is not yet in drm-misc-fixes :(

-Paul

> >  Fixes: c369cb27c267 ("drm/ingenic: Support multiple panels/bridges")
> >  Cc: <stable@xxxxxxxxxxxxxxx> # 5.8+
> >  Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> >  ---
> >   drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 10 ++++++++++
> >   1 file changed, 10 insertions(+)
> >
> >  diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c 
> > b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> >  index 368bfef8b340..d23a3292a0e0 100644
> >  --- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> >  +++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> >  @@ -803,6 +803,11 @@ static void __maybe_unused 
> > ingenic_drm_release_rmem(void *d)
> >   	of_reserved_mem_device_release(d);
> >   }
> >
> >  +static void ingenic_drm_encoder_cleanup(void *encoder)
> >  +{
> >  +	drm_encoder_cleanup(encoder);
> >  +}
> >  +
> >   static int ingenic_drm_bind(struct device *dev, bool 
> > has_components)
> >   {
> >   	struct platform_device *pdev = to_platform_device(dev);
> >  @@ -1011,6 +1016,11 @@ static int ingenic_drm_bind(struct device 
> > *dev, bool has_components)
> >   			return ret;
> >   		}
> >
> >  +		ret = devm_add_action_or_reset(dev, ingenic_drm_encoder_cleanup,
> >  +					       encoder);
> >  +		if (ret)
> >  +			return ret;
> >  +
> >   		ret = drm_bridge_attach(encoder, bridge, NULL, 0);
> >   		if (ret) {
> >   			dev_err(dev, "Unable to attach bridge\n");
>
> --
> Regards,
>
> Laurent Pinchart