linux-kernel - Re: [PATCH] drm/bridge: sii902x: Variable status in sii902x_connector_detect() could be uninitialized if regmap

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Message-ID: <20190930231948.GB10149@pendragon.ideasonboard.com>
Date:   Fri, 4 Oct 2019 10:02:31 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Yizhuo <yzhai003@....edu>
Cc:     csong@...ucr.edu, zhiyunq@...ucr.edu,
        Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/bridge: sii902x: Variable status in
 sii902x_connector_detect() could be uninitialized if regmap_read() fails

Hi Yizhuo,

Thank you for the patch.

On Sun, Sep 29, 2019 at 09:45:02PM -0700, Yizhuo wrote:
> In function sii902x_connector_detect(), variable "status" could be
> initialized if regmap_read() fails. However, "status" is used to

I assume you meant "could be uninitialized" ?

> decide the return value, which is potentially unsafe.
> 
> Signed-off-by: Yizhuo <yzhai003@....edu>
> ---
>  drivers/gpu/drm/bridge/sii902x.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/bridge/sii902x.c b/drivers/gpu/drm/bridge/sii902x.c
> index 38f75ac580df..afce64f51ff2 100644
> --- a/drivers/gpu/drm/bridge/sii902x.c
> +++ b/drivers/gpu/drm/bridge/sii902x.c
> @@ -246,7 +246,7 @@ static enum drm_connector_status
>  sii902x_connector_detect(struct drm_connector *connector, bool force)
>  {
>  	struct sii902x *sii902x = connector_to_sii902x(connector);
> -	unsigned int status;
> +	unsigned int status = 0;
>  
>  	mutex_lock(&sii902x->mutex);

I'll add a bit more context:

> 	regmap_read(sii902x->regmap, SII902X_INT_STATUS, &status);
>
> 	mutex_unlock(&sii902x->mutex);
>
> 	return (status & SII902X_PLUGGED_STATUS) ?
> 	       connector_status_connected : connector_status_disconnected;

If regmap read fails, shouldn't we return connector_status_unknown ?

-- 
Regards,

Laurent Pinchart