linux-kernel - Re: [PATCH v2] drm: rcar-du: fix possible object reference leak

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Date:   Mon, 8 Apr 2019 14:15:54 +0530
From:   Mukesh Ojha <mojha@...eaurora.org>
To:     Wen Yang <wen.yang99@....com.cn>, linux-kernel@...r.kernel.org
Cc:     wang.yi59@....com.cn,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH v2] drm: rcar-du: fix possible object reference leak


On 4/8/2019 8:28 AM, Wen Yang wrote:
> The call to of_get_parent returns a node pointer with refcount
> incremented thus it must be explicitly decremented after the last
> usage.
>
> Detected by coccinelle with the following warnings:
> drivers/gpu/drm/rcar-du/rcar_du_of.c:235:2-8: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 216, but without a corresponding object release within this function.
> drivers/gpu/drm/rcar-du/rcar_du_of.c:236:2-8: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 209, but without a corresponding object release within this function.
>
> Signed-off-by: Wen Yang <wen.yang99@....com.cn>
> Suggested-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> Cc: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> Cc: Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
> Cc: David Airlie <airlied@...ux.ie>
> Cc: Daniel Vetter <daniel@...ll.ch>
> Cc: dri-devel@...ts.freedesktop.org
> Cc: linux-renesas-soc@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org (open list)
> ---
> v2->v1: turn the return into a goto done.
>
>   drivers/gpu/drm/rcar-du/rcar_du_of.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_of.c b/drivers/gpu/drm/rcar-du/rcar_du_of.c
> index afef696..782bfc7 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_of.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_of.c
> @@ -232,7 +232,7 @@ static void __init rcar_du_of_lvds_patch(const struct of_device_id *of_ids)
>   	lvds_node = of_find_compatible_node(NULL, NULL, compatible);
>   	if (lvds_node) {
>   		of_node_put(lvds_node);
> -		return;
> +		goto done;
>   	}
>   


you might have to create multiple level to do handling it.. there are 
unnecessary put being done on "done" which is not valid

for this case.

-Mukesh

>   	/*