Re: [PATCH v2] drm/msm/adreno: fix userspace-triggered crash on a2xx-a4xx

[Akhil P Oommen <akhilpo@oss.qualcomm.com>]

On 4/7/2026 8:53 AM, Dmitry Baryshkov wrote:
> Before a5xx Adreno driver will not try fetching UBWC params (because
> those generations didn't support UBWC anyway), however it's still
> possible to query UBWC-related params from the userspace, triggering
> possible NULL pointer dereference. Check for UBWC config in
> adreno_get_param() and return sane defaults if there is none.
> 
> Fixes: a452510aad53 ("drm/msm/adreno: Switch to the common UBWC config struct")
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

Reviewed-by: Akhil P Oommen <akhilpo@oss.qualcomm.com>

-Akhil

> ---
> Changes in v2:
> - Changed adreno_get_param() return -ENOENT for affected params (Rob)
> - Link to v1: https://patch.msgid.link/20260407-adreno-fix-ubwc-v1-1-bb2b09450b87@oss.qualcomm.com
> ---
>  drivers/gpu/drm/msm/adreno/adreno_gpu.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> index d5fe6f6f0dec..34e4ab43b0f6 100644
> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> @@ -426,15 +426,21 @@ int adreno_get_param(struct msm_gpu *gpu, struct msm_context *ctx,
>  		*value = vm->mm_range;
>  		return 0;
>  	case MSM_PARAM_HIGHEST_BANK_BIT:
> +		if (!adreno_gpu->ubwc_config)
> +			return -ENOENT;
>  		*value = adreno_gpu->ubwc_config->highest_bank_bit;
>  		return 0;
>  	case MSM_PARAM_RAYTRACING:
>  		*value = adreno_gpu->has_ray_tracing;
>  		return 0;
>  	case MSM_PARAM_UBWC_SWIZZLE:
> +		if (!adreno_gpu->ubwc_config)
> +			return -ENOENT;
>  		*value = adreno_gpu->ubwc_config->ubwc_swizzle;
>  		return 0;
>  	case MSM_PARAM_MACROTILE_MODE:
> +		if (!adreno_gpu->ubwc_config)
> +			return -ENOENT;
>  		*value = adreno_gpu->ubwc_config->macrotile_mode;
>  		return 0;
>  	case MSM_PARAM_UCHE_TRAP_BASE:
> 
> ---
> base-commit: 36ece9697e89016181e5ae87510e40fb31d86f2b
> change-id: 20260407-adreno-fix-ubwc-6a2564710e21
> 
> Best regards,
> --  
> With best wishes
> Dmitry
>