On Mon, Jan 18, 2021 at 11:37:49AM +0000, Paul Cercueil wrote:
> 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 :(
Well I think then we should only fix this in drm-misc-next. Adding more
broken usage of devm_ isn't really a good idea.
If you want this in -fixes, then I think hand-roll it. But devm_ for drm
objects really is the wrong fix.
-Daniel
>
> -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
>
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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