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Subject: Re: [PATCH] drm: mxsfb: Check NULL pointer
To:     Jiasheng Jiang <jiasheng@iscas.ac.cn>, stefan@agner.ch,
        airlied@linux.ie, daniel@ffwll.ch, shawnguo@kernel.org,
        s.hauer@pengutronix.de, kernel@pengutronix.de, festevam@gmail.com,
        linux-imx@nxp.com
Cc:     dri-devel@lists.freedesktop.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
References: <1635925699-3414834-1-git-send-email-jiasheng@iscas.ac.cn>
From:   Marek Vasut <marex@denx.de>
Message-ID: <579998fc-12ee-fb23-afe5-f0ef70807a3c@denx.de>
Date:   Wed, 3 Nov 2021 08:58:16 +0100
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On 11/3/21 8:48 AM, Jiasheng Jiang wrote:
> As we see in the drm_connector_list_iter_next(), it could return
> NULL. In order to avoid the use of the NULL pointer, it may be
> better to check the return value.
> 
> Fixes: c42001e ("drm: mxsfb: Use drm_panel_bridge")
> Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
> ---
>   drivers/gpu/drm/mxsfb/mxsfb_drv.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.c b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
> index 6da9355..b875c11 100644
> --- a/drivers/gpu/drm/mxsfb/mxsfb_drv.c
> +++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
> @@ -145,6 +145,8 @@ static int mxsfb_attach_bridge(struct mxsfb_drm_private *mxsfb)
>   	 */
>   	drm_connector_list_iter_begin(drm, &iter);
>   	mxsfb->connector = drm_connector_list_iter_next(&iter);
> +	if (!mxsfb->connector)
> +		return 1;

In which case does this happen failure happen ?
What is the test case ?