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

[Dmitry Baryshkov]

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@xxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/msm/adreno/adreno_gpu.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
index d5fe6f6f0dec..7dc95c0a17f7 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
@@ -426,16 +426,25 @@ int adreno_get_param(struct msm_gpu *gpu, struct msm_context *ctx,
 		*value = vm->mm_range;
 		return 0;
 	case MSM_PARAM_HIGHEST_BANK_BIT:
-		*value = adreno_gpu->ubwc_config->highest_bank_bit;
+		if (!adreno_gpu->ubwc_config)
+			*value = 13;
+		else
+			*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:
-		*value = adreno_gpu->ubwc_config->ubwc_swizzle;
+		if (!adreno_gpu->ubwc_config)
+			*value = 0;
+		else
+			*value = adreno_gpu->ubwc_config->ubwc_swizzle;
 		return 0;
 	case MSM_PARAM_MACROTILE_MODE:
-		*value = adreno_gpu->ubwc_config->macrotile_mode;
+		if (!adreno_gpu->ubwc_config)
+			*value = 0;
+		else
+			*value = adreno_gpu->ubwc_config->macrotile_mode;
 		return 0;
 	case MSM_PARAM_UCHE_TRAP_BASE:
 		*value = adreno_gpu->uche_trap_base;

---
base-commit: 36ece9697e89016181e5ae87510e40fb31d86f2b
change-id: 20260407-adreno-fix-ubwc-6a2564710e21

Best regards,
--  
With best wishes
Dmitry