linux-kernel - Re: [PATCH 1/7] drm/mediatek: fix possible object reference leak

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Date:   Tue, 9 Apr 2019 13:15:59 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     Wen Yang <wen.yang99@....com.cn>
CC:     <linux-kernel@...r.kernel.org>, <wang.yi59@....com.cn>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Matthias Brugger <matthias.bgg@...il.com>,
        <dri-devel@...ts.freedesktop.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH 1/7] drm/mediatek: fix possible object reference leak

Hi, Wen:

On Thu, 2019-04-04 at 00:04 +0800, Wen Yang wrote:
> The call to of_parse_phandle 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/mediatek/mtk_hdmi.c:1521:2-8: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 1509, but without a corresponding object release within this function.
> drivers/gpu/drm/mediatek/mtk_hdmi.c:1524:1-7: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 1509, but without a corresponding object release within this function.

For this patch, applied to mediatek-drm-fixes-5.1 [1], thanks.

[1]
https://github.com/ckhu-mediatek/linux.git-tags/commits/mediatek-drm-fixes-5.1

Regards,
CK

> 
> Signed-off-by: Wen Yang <wen.yang99@....com.cn>
> Cc: CK Hu <ck.hu@...iatek.com>
> Cc: Philipp Zabel <p.zabel@...gutronix.de>
> Cc: David Airlie <airlied@...ux.ie>
> Cc: Daniel Vetter <daniel@...ll.ch>
> Cc: Matthias Brugger <matthias.bgg@...il.com>
> Cc: dri-devel@...ts.freedesktop.org
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-mediatek@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org
> ---
>  drivers/gpu/drm/mediatek/mtk_hdmi.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi.c b/drivers/gpu/drm/mediatek/mtk_hdmi.c
> index 915cc84..ed10f4d 100644
> --- a/drivers/gpu/drm/mediatek/mtk_hdmi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_hdmi.c
> @@ -1516,6 +1516,7 @@ static int mtk_hdmi_dt_parse_pdata(struct mtk_hdmi *hdmi,
>  	of_node_put(remote);
>  
>  	hdmi->ddc_adpt = of_find_i2c_adapter_by_node(i2c_np);
> +	of_node_put(i2c_np);
>  	if (!hdmi->ddc_adpt) {
>  		dev_err(dev, "Failed to get ddc i2c adapter by node\n");
>  		return -EINVAL;