[PATCH v6 1/3] drm: adv7511: Fix use-after-free in adv7533_attach_dsi()

[Biju Das]

Hi Laurent,

Thank you for the feedback.

> -----Original Message-----
> From: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Sent: 19 November 2024 19:03
> Subject: Re: [PATCH v6 1/3] drm: adv7511: Fix use-after-free in adv7533_attach_dsi()
> 
> Hi Biju,
> 
> Thank you for the patch.
> 
> On Tue, Nov 19, 2024 at 06:44:14PM +0000, Biju Das wrote:
> > The host_node pointer was assigned and freed in adv7533_parse_dt(),
> > and later, adv7533_attach_dsi() uses the same. Fix this use-after-free
> > issue by dropping of_node_put() in adv7533_parse_dt() and calling
> > of_node_put() in error path of probe() and also in the remove().
> >
> > Fixes: 1e4d58cd7f88 ("drm/bridge: adv7533: Create a MIPI DSI device")
> > Cc: stable at vger.kernel.org
> > Signed-off-by: Biju Das <biju.das.jz at bp.renesas.com>
> > ---
> > Changes in v6:
> >  - Fixed memory leak by adding goto stattement in error path of
> >    adv7511_init_regulators().
> > Changes in v5:
> >  - Updated commit description.
> >  - restored host_node in struct adv7511.
> >  - Dropped of_node_put() in adv7533_parse_dt() and calling of_node_put()
> >    in error path of probe() and also in the remove().
> > Changes in v4:
> >  - Updated commit description.
> >  - Dropped host_node from struct adv7511 and instead used a local pointer
> >    in probe(). Also freeing of host_node pointer after use is done in
> >    probe().
> > Changes in v3:
> >  - Replace __free construct with readable of_node_put().
> > Changes in v2:
> >  - Added the tag "Cc: stable at vger.kernel.org" in the sign-off area.
> >  - Dropped Archit Taneja invalid Mail address
> > ---
> >  drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 12 ++++++++++--
> >  drivers/gpu/drm/bridge/adv7511/adv7533.c     |  2 --
> >  2 files changed, 10 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > index eb5919b38263..f5525c12f0cd 100644
> > --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > @@ -1241,8 +1241,10 @@ static int adv7511_probe(struct i2c_client *i2c)
> >  		return ret;
> >
> >  	ret = adv7511_init_regulators(adv7511);
> > -	if (ret)
> > -		return dev_err_probe(dev, ret, "failed to init regulators\n");
> > +	if (ret) {
> > +		dev_err_probe(dev, ret, "failed to init regulators\n");
> > +		goto err_of_node_put;
> > +	}
> >
> >  	/*
> >  	 * The power down GPIO is optional. If present, toggle it from
> > active to @@ -1363,6 +1365,9 @@ static int adv7511_probe(struct i2c_client *i2c)
> >  	i2c_unregister_device(adv7511->i2c_edid);
> >  uninit_regulators:
> >  	adv7511_uninit_regulators(adv7511);
> > +err_of_node_put:
> > +	if (adv7511->host_node)
> 
> I forgot to mention that you can drop the check here, as of_node_put() is a no-op when called with a
> NULL pointer. Sorry about that.

I also missed it. Will fix it in next version.

Cheers,
Biju

> 
> > +		of_node_put(adv7511->host_node);
> >
> >  	return ret;
> >  }
> > @@ -1371,6 +1376,9 @@ static void adv7511_remove(struct i2c_client
> > *i2c)  {
> >  	struct adv7511 *adv7511 = i2c_get_clientdata(i2c);
> >
> > +	if (adv7511->host_node)
> 
> Same here.
> 
> With this addressed,
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas at ideasonboard.com>
> 
> > +		of_node_put(adv7511->host_node);
> > +
> >  	adv7511_uninit_regulators(adv7511);
> >
> >  	drm_bridge_remove(&adv7511->bridge);
> > diff --git a/drivers/gpu/drm/bridge/adv7511/adv7533.c
> > b/drivers/gpu/drm/bridge/adv7511/adv7533.c
> > index 4481489aaf5e..5f195e91b3e6 100644
> > --- a/drivers/gpu/drm/bridge/adv7511/adv7533.c
> > +++ b/drivers/gpu/drm/bridge/adv7511/adv7533.c
> > @@ -181,8 +181,6 @@ int adv7533_parse_dt(struct device_node *np, struct adv7511 *adv)
> >  	if (!adv->host_node)
> >  		return -ENODEV;
> >
> > -	of_node_put(adv->host_node);
> > -
> >  	adv->use_timing_gen = !of_property_read_bool(np,
> >  						"adi,disable-timing-generator");
> >
> 
> --
> Regards,
> 
> Laurent Pinchart