linux-kernel - Re: [PATCH v2] drm/of: free the iterator object on failure

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Date:   Wed, 14 Jul 2021 18:26:48 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Steven Price <steven.price@....com>
Cc:     Daniel Vetter <daniel@...ll.ch>, David Airlie <airlied@...ux.ie>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Biju Das <biju.das.jz@...renesas.com>,
        Pavel Machek <pavel@...x.de>
Subject: Re: [PATCH v2] drm/of: free the iterator object on failure

Hi Steven,

Thank you for the patch.

On Wed, Jul 14, 2021 at 03:33:00PM +0100, Steven Price wrote:
> When bailing out due to the sanity check the iterator value needs to be
> freed because the early return prevents for_each_child_of_node() from
> doing the dereference itself.
> 
> Fixes: 6529007522de ("drm: of: Add drm_of_lvds_get_dual_link_pixel_order")
> Signed-off-by: Steven Price <steven.price@....com>

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

> ---
>  drivers/gpu/drm/drm_of.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> v2: Fixes now refers to the original commit as suggested by Laurent, rather
> than 4ee48cc5586b ("drm: of: Fix double-free bug") which only fixed part of
> the problem. Note that 4ee48cc5586b is a dependency for this patch to
> cleanly apply.
> 
> diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
> index 197c57477344..997b8827fed2 100644
> --- a/drivers/gpu/drm/drm_of.c
> +++ b/drivers/gpu/drm/drm_of.c
> @@ -331,8 +331,10 @@ static int drm_of_lvds_get_remote_pixels_type(
>  		 * configurations by passing the endpoints explicitly to
>  		 * drm_of_lvds_get_dual_link_pixel_order().
>  		 */
> -		if (!current_pt || pixels_type != current_pt)
> +		if (!current_pt || pixels_type != current_pt) {
> +			of_node_put(endpoint);
>  			return -EINVAL;
> +		}
>  	}
>  
>  	return pixels_type;

-- 
Regards,

Laurent Pinchart