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

[Laurent Pinchart]

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.

> +		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