linux-kernel - Re: [PATCH][next] drm/mediatek: avoid dereferencing a null hdmi

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Message-ID: <20201208125549.GG8403@vkoul-mobl>
Date:   Tue, 8 Dec 2020 18:25:49 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Chunfeng Yun <chunfeng.yun@...iatek.com>
Cc:     Colin King <colin.king@...onical.com>,
        Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Kishon Vijay Abraham I <kishon@...com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        CK Hu <ck.hu@...iatek.com>,
        chunhui dai <chunhui.dai@...iatek.com>,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] drm/mediatek: avoid dereferencing a null hdmi_phy
 on an error message

On 08-12-20, 09:50, Chunfeng Yun wrote:
> On Mon, 2020-12-07 at 15:09 +0000, Colin King wrote:
> > From: Colin Ian King <colin.king@...onical.com>
> > 
> > Currently there is a null pointer check for hdmi_phy that implies it
> > may be null, however a dev_err messages dereferences this potential null
> > pointer.  Avoid a null pointer dereference by only emitting the dev_err
> > message if hdmi_phy is non-null.  It is a moot point if the error message
> > needs to be printed at all, but since this is a relatively new piece of
> > code it may be useful to keep the message in for the moment in case there
> > are unforseen errors that need to be reported.
> > 
> > Addresses-Coverity: ("Dereference after null check")
> > Fixes: be28b6507c46 ("drm/mediatek: separate hdmi phy to different file")
> > Signed-off-by: Colin Ian King <colin.king@...onical.com>
> > ---
> >  drivers/phy/mediatek/phy-mtk-hdmi.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/phy/mediatek/phy-mtk-hdmi.c b/drivers/phy/mediatek/phy-mtk-hdmi.c
> > index c5c61f5a9ea0..5184054783c7 100644
> > --- a/drivers/phy/mediatek/phy-mtk-hdmi.c
> > +++ b/drivers/phy/mediatek/phy-mtk-hdmi.c
> > @@ -84,8 +84,9 @@ mtk_hdmi_phy_dev_get_ops(const struct mtk_hdmi_phy *hdmi_phy)
> >  	    hdmi_phy->conf->hdmi_phy_disable_tmds)
> >  		return &mtk_hdmi_phy_dev_ops;
> >  
> > -	dev_err(hdmi_phy->dev, "Failed to get dev ops of phy\n");
> > -		return NULL;
> > +	if (hdmi_phy)
> > +		dev_err(hdmi_phy->dev, "Failed to get dev ops of phy\n");
> > +			return NULL;
> indentation: one tab before return

I have applied this and fixed the indent while applying

-- 
~Vinod