linux-kernel - Re: [PATCH 1/3] drm: rcar-du: add missing of_node

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 14 Jan 2019 14:34:06 +0000
From:   Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
To:     Julia Lawall <Julia.Lawall@...6.fr>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     kernel-janitors@...r.kernel.org, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-renesas-soc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] drm: rcar-du: add missing of_node_put

Hi Julia,

Thank you for the patch,

On 13/01/2019 09:44, Julia Lawall wrote:
> Add an of_node_put when the result of of_graph_get_remote_port_parent is
> not available.
> 
> The semantic match that finds this problem is as follows
> (http://coccinelle.lip6.fr):
> 
> // <smpl>
> @r exists@
> local idexpression e;
> expression x;
> @@
> e = of_graph_get_remote_port_parent(...);
> ... when != x = e
>     when != true e == NULL
>     when != of_node_put(e)
>     when != of_fwnode_handle(e)
> (
> return e;
> |
> *return ...;
> )
> // </smpl>
> 

For this part at least:

Reviewed-by: Kieran Bingham <kieran.bingham+renesas@...asonboard.com>

But a little discussion below:


> Signed-off-by: Julia Lawall <Julia.Lawall@...6.fr>

This does indeed look like a missing of_node_put() but I don't think it
will be the only one in that code. It gets a bit tangled - and I think
there's possibly another missing put on the error path of

        if (!encoder) {
                dev_warn(rcdu->dev,
                         "no encoder found for endpoint %pOF, skipping\n",
                         ep->local_node);
                return -ENODEV;
        }

because that implies that no encoder was found, and thus -
                encoder = entity;

was not executed, and the tail of that function calls:

         of_node_put(encoder);

which would have been the final of_node_put(entity)


I think that part could be considered separate to this patch, but it's
also quite closely related. Either way - I think it needs a second pair
of eyes to see if I'm not crazy :)

Regards

Kieran

> 
> ---
>  drivers/gpu/drm/rcar-du/rcar_du_kms.c |    1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> index 9c7007d..bc3fcb3 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> @@ -331,6 +331,7 @@ static int rcar_du_encoders_init_one(struct rcar_du_device *rcdu,
>  		dev_dbg(rcdu->dev,
>  			"connected entity %pOF is disabled, skipping\n",
>  			entity);
> +		of_node_put(entity);
>  		return -ENODEV;
>  	}
>  
>