[PATCH] drm/msm: Fix potential Oops in a6xx_gmu_rpmh_init()

[Dmitry Baryshkov]

On 04/10/2021 16:45, Dan Carpenter wrote:
> There are two problems here:
> 1) The "seqptr" is used uninitalized when we free it at the end.

This looks like a nice catch, potentially causing troubles.

> 2) The a6xx_gmu_get_mmio() function returns error pointers.  It never
>     returns true.
> 
> Fixes: 64245fc55172 ("drm/msm/a6xx: use AOP-initialized PDC for a650")
> Fixes: f8fc924e088e ("drm/msm/a6xx: Fix PDC register overlap")
> Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>

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

> ---
>   drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> index a7c58018959f..3bd6e579ea89 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> @@ -512,11 +512,11 @@ static void a6xx_gmu_rpmh_init(struct a6xx_gmu *gmu)
>   	struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
>   	struct platform_device *pdev = to_platform_device(gmu->dev);
>   	void __iomem *pdcptr = a6xx_gmu_get_mmio(pdev, "gmu_pdc");
> -	void __iomem *seqptr;
> +	void __iomem *seqptr = NULL;
>   	uint32_t pdc_address_offset;
>   	bool pdc_in_aop = false;
>   
> -	if (!pdcptr)
> +	if (IS_ERR(pdcptr))
>   		goto err;
>   
>   	if (adreno_is_a650(adreno_gpu) || adreno_is_a660_family(adreno_gpu))
> @@ -528,7 +528,7 @@ static void a6xx_gmu_rpmh_init(struct a6xx_gmu *gmu)
>   
>   	if (!pdc_in_aop) {
>   		seqptr = a6xx_gmu_get_mmio(pdev, "gmu_pdc_seq");
> -		if (!seqptr)
> +		if (IS_ERR(seqptr))
>   			goto err;
>   	}
>   
> 


-- 
With best wishes
Dmitry