linux-kernel - Re: [PATCH 4/7] drm/omap: fix possible object reference leak

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Date:   Thu, 4 Apr 2019 16:25:29 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Wen Yang <wen.yang99@....com.cn>
Cc:     linux-kernel@...r.kernel.org, wang.yi59@....com.cn,
        Tomi Valkeinen <tomi.valkeinen@...com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Sebastian Reichel <sebastian.reichel@...labora.com>,
        dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH 4/7] drm/omap: fix possible object reference leak

Hello Wen,

Thank you for the patch.

On Thu, Apr 04, 2019 at 12:04:12AM +0800, Wen Yang wrote:
> The call to of_find_matching_node 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/omapdrm/dss/omapdss-boot-init.c:212:2-8: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 209, but without a corresponding object release within this function.
> drivers/gpu/drm/omapdrm/dss/omapdss-boot-init.c:237:1-7: 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>
> Cc: Tomi Valkeinen <tomi.valkeinen@...com>
> Cc: David Airlie <airlied@...ux.ie>
> Cc: Daniel Vetter <daniel@...ll.ch>
> Cc: Sebastian Reichel <sebastian.reichel@...labora.com>
> Cc: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> Cc: dri-devel@...ts.freedesktop.org
> Cc: linux-kernel@...r.kernel.org

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

Would you like to get the series merged in one go, or individual patches
picked by the respective maintainer ?

> ---
>  drivers/gpu/drm/omapdrm/dss/omapdss-boot-init.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/omapdrm/dss/omapdss-boot-init.c b/drivers/gpu/drm/omapdrm/dss/omapdss-boot-init.c
> index 2b41c75..60067e8 100644
> --- a/drivers/gpu/drm/omapdrm/dss/omapdss-boot-init.c
> +++ b/drivers/gpu/drm/omapdrm/dss/omapdss-boot-init.c
> @@ -208,8 +208,10 @@ static int __init omapdss_boot_init(void)
>  
>  	dss = of_find_matching_node(NULL, omapdss_of_match);
>  
> -	if (dss == NULL || !of_device_is_available(dss))
> +	if (dss == NULL || !of_device_is_available(dss)) {
> +		of_node_put(dss);
>  		return 0;
> +	}
>  
>  	omapdss_walk_device(dss, true);
>  
> @@ -234,6 +236,7 @@ static int __init omapdss_boot_init(void)
>  		kfree(n);
>  	}
>  
> +	of_node_put(dss);
>  	return 0;
>  }
>  

-- 
Regards,

Laurent Pinchart