[PATCH v5 1/3] drm: adv7511: Fix use-after-free in adv7533_attach_dsi()

[Biju Das]

Hi Laurent,

> -----Original Message-----
> From: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Sent: 19 November 2024 16:28
> Subject: Re: [PATCH v5 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 01:10:03PM +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 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 | 5 +++++
> >  drivers/gpu/drm/bridge/adv7511/adv7533.c     | 2 --
> >  2 files changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > index eb5919b38263..6cfdda04f52f 100644
> > --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > @@ -1363,6 +1363,8 @@ static int adv7511_probe(struct i2c_client *i2c)
> >  	i2c_unregister_device(adv7511->i2c_edid);
> >  uninit_regulators:
> >  	adv7511_uninit_regulators(adv7511);
> > +	if (adv7511->host_node)
> > +		of_node_put(adv7511->host_node);
> 
> This won't be called when adv7511_init_regulators() fails as the driver returns directly then, leaking
> the reference. You need a new error label and a goto for that error path.

Oops missed again.
> 
> In the future, when touching error handling, please try to check existing error paths and verify
> they're still right.

Yes, will take care next time.

Cheers,
Biju

> 
> >
> >  	return ret;
> >  }
> > @@ -1371,6 +1373,9 @@ static void adv7511_remove(struct i2c_client
> > *i2c)  {
> >  	struct adv7511 *adv7511 = i2c_get_clientdata(i2c);
> >
> > +	if (adv7511->host_node)
> > +		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