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From:   Benjamin Gaignard <benjamin.gaignard@linaro.org>
Date:   Wed, 13 Feb 2019 10:07:38 +0100
Message-ID: <CA+M3ks7EO-Fy4KFEu5NgpsK73z2BsEhEsBZ8qraFoPnT7nTVLQ@mail.gmail.com>
Subject: Re: [PATCH v2 4/4] media: platform: sti: fix possible object
 reference leak
To:     Wen Yang <wen.yang99@zte.com.cn>
Cc:     Mauro Carvalho Chehab <mchehab@kernel.org>,
        linux-media@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        xue.zhihong@zte.com.cn, wang.yi59@zte.com.cn,
        "Hans Verkuil (hansverk)" <hansverk@cisco.com>,
        Wen Yang <yellowriver2010@hotmail.com>
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Le mer. 13 f=C3=A9vr. 2019 =C3=A0 00:49, Wen Yang <wen.yang99@zte.com.cn> a=
 =C3=A9crit :
>
> The call to of_parse_phandle() returns a node pointer with refcount
> incremented thus it must be explicitly decremented here after the last
> usage.
> The of_find_device_by_node() takes a reference to the underlying device
> structure, we also should release that reference.
>
> Hans Verkuil says:
> The cec driver should never take a reference of the hdmi device.
> It never accesses the HDMI device, it only needs the HDMI device pointer =
as
> a key in the notifier list.
> The real problem is that several CEC drivers take a reference of the HDMI
> device and never release it. So those drivers need to be fixed.
>
> This patch fixes those two issues.

Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>

>
> Fixes: fc4e009c6c98 ("[media] stih-cec: add CEC notifier support")
> Suggested-by: Hans Verkuil (hansverk) <hansverk@cisco.com>
> Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
> Cc: Hans Verkuil (hansverk) <hansverk@cisco.com>
> Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org>
> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
> Cc: Wen Yang <yellowriver2010@hotmail.com>
> Cc: linux-media@vger.kernel.org
> ---
> v2->v1:
> - move of_node_put() to just after the 'hdmi_dev =3D of_find_device_by_no=
de(np)'.
> - put_device() can be done before the cec =3D devm_kzalloc line.
>
>  drivers/media/platform/sti/cec/stih-cec.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/media/platform/sti/cec/stih-cec.c b/drivers/media/pl=
atform/sti/cec/stih-cec.c
> index d34099f..721021f 100644
> --- a/drivers/media/platform/sti/cec/stih-cec.c
> +++ b/drivers/media/platform/sti/cec/stih-cec.c
> @@ -317,9 +317,11 @@ static int stih_cec_probe(struct platform_device *pd=
ev)
>         }
>
>         hdmi_dev =3D of_find_device_by_node(np);
> +       of_node_put(np);
>         if (!hdmi_dev)
>                 return -EPROBE_DEFER;
>
> +       put_device(&hdmi_dev->dev);
>         cec->notifier =3D cec_notifier_get(&hdmi_dev->dev);
>         if (!cec->notifier)
>                 return -ENOMEM;
> --
> 2.9.5
>