[PATCH][next] drm/mediatek: avoid dereferencing a null hdmi_phy on an error message

[PATCH][next] drm/mediatek: avoid dereferencing a null hdmi_phy on an error message

[Colin King]

From: Colin Ian King <colin.king@canonical.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@canonical.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;
 }
 
 static void mtk_hdmi_phy_clk_get_data(struct mtk_hdmi_phy *hdmi_phy,
-- 
2.29.2


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Re: [PATCH][next] drm/mediatek: avoid dereferencing a null hdmi_phy on an error message

[Chunfeng Yun]

On Mon, 2020-12-07 at 15:09 +0000, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.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@canonical.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

Thanks

>  }
>  
>  static void mtk_hdmi_phy_clk_get_data(struct mtk_hdmi_phy *hdmi_phy,

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Re: [PATCH][next] drm/mediatek: avoid dereferencing a null hdmi_phy on an error message

[Vinod Koul]

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@canonical.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@canonical.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

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