Re: [PATCH v2] drm/msm: Fix NULL deref in adreno_load_gpu

[Jordan Crouse <jcrouse@codeaurora.org>]

On Fri, Dec 22, 2017 at 03:41:13PM +0530, Archit Taneja wrote:
> The msm/kms driver should work even if there is no GPU device specified
> in DT. Currently, we get a NULL dereference crash in adreno_load_gpu
> since the driver assumes that priv->gpu_pdev is non-NULL.
> 
> Perform an additional check on priv->gpu_pdev before trying to retrieve
> the msm_gpu pointer from it.
> 
> v2: Incorporate Jordan's comments:
> - Simplify the check to share the same error message.
> - Use dev_err_once() to avoid an error message every time we open the
>   drm device fd.
> 
> Fixes: eec874ce5ff1 (drm/msm/adreno: load gpu at probe/bind time)
> 
> Signed-off-by: Archit Taneja <architt@codeaurora.org>

Acked-by: Jordan Crouse <jcrouse@codeaurora.org>

> ---
>  drivers/gpu/drm/msm/adreno/adreno_device.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/adreno_device.c b/drivers/gpu/drm/msm/adreno/adreno_device.c
> index 05022ea2a007..bfb3d689f47d 100644
> --- a/drivers/gpu/drm/msm/adreno/adreno_device.c
> +++ b/drivers/gpu/drm/msm/adreno/adreno_device.c
> @@ -125,11 +125,14 @@ struct msm_gpu *adreno_load_gpu(struct drm_device *dev)
>  {
>  	struct msm_drm_private *priv = dev->dev_private;
>  	struct platform_device *pdev = priv->gpu_pdev;
> -	struct msm_gpu *gpu = platform_get_drvdata(priv->gpu_pdev);
> +	struct msm_gpu *gpu = NULL;
>  	int ret;
>  
> +	if (pdev)
> +		gpu = platform_get_drvdata(pdev);
> +
>  	if (!gpu) {
> -		dev_err(dev->dev, "no adreno device\n");
> +		dev_err_once(dev->dev, "no GPU device was found\n");
>  		return NULL;
>  	}

-- 
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