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Subject: Re: [PATCH] drm/msm: Fix null pointer dereference on pointer edp
To:     Colin King <colin.king@canonical.com>,
        Rob Clark <robdclark@gmail.com>, Sean Paul <sean@poorly.run>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Dave Airlie <airlied@redhat.com>,
        Lyude Paul <lyude@redhat.com>, linux-arm-msm@vger.kernel.org,
        dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org
Cc:     kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20210929121857.213922-1-colin.king@canonical.com>
From:   Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Message-ID: <c9a68b02-d9b6-e779-7659-2f92639e55b0@linaro.org>
Date:   Fri, 1 Oct 2021 21:34:50 +0300
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On 29/09/2021 15:18, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> The initialization of pointer dev dereferences pointer edp before
> edp is null checked, so there is a potential null pointer deference
> issue. Fix this by only dereferencing edp after edp has been null
> checked.
> 
> Addresses-Coverity: ("Dereference before null check")
> Fixes: ab5b0107ccf3 ("drm/msm: Initial add eDP support in msm drm driver (v5)")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

> ---
>   drivers/gpu/drm/msm/edp/edp_ctrl.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/edp/edp_ctrl.c b/drivers/gpu/drm/msm/edp/edp_ctrl.c
> index 4fb397ee7c84..fe1366b4c49f 100644
> --- a/drivers/gpu/drm/msm/edp/edp_ctrl.c
> +++ b/drivers/gpu/drm/msm/edp/edp_ctrl.c
> @@ -1116,7 +1116,7 @@ void msm_edp_ctrl_power(struct edp_ctrl *ctrl, bool on)
>   int msm_edp_ctrl_init(struct msm_edp *edp)
>   {
>   	struct edp_ctrl *ctrl = NULL;
> -	struct device *dev = &edp->pdev->dev;
> +	struct device *dev;
>   	int ret;
>   
>   	if (!edp) {
> @@ -1124,6 +1124,7 @@ int msm_edp_ctrl_init(struct msm_edp *edp)
>   		return -EINVAL;
>   	}
>   
> +	dev = &edp->pdev->dev;
>   	ctrl = devm_kzalloc(dev, sizeof(*ctrl), GFP_KERNEL);
>   	if (!ctrl)
>   		return -ENOMEM;
> 


-- 
With best wishes
Dmitry