drm/amd/display: Verify Gamma & Degamma LUT sizes in amdgpu_dm_atomic_check

For each CRTC state, check the size of Gamma and Degamma LUTs  so
unexpected and larger sizes wouldn't slip through.

TEST: IGT:kms_color::pipe-invalid-gamma-lut-sizes

v2: fix assignments in if clauses, Mark's email.
Reviewed-by: NHarry Wentland <harry.wentland@amd.com>
Signed-off-by: NMark Yacoub <markyacoub@chromium.org>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -10245,6 +10245,10 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
 			dm_old_crtc_state->dsc_force_changed == false)
 			continue;
 
+		ret = amdgpu_dm_verify_lut_sizes(new_crtc_state);
+		if (ret)
+			goto fail;
+
 		if (!new_crtc_state->enable)
 			continue;
 

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h

@@ -617,6 +617,7 @@ void amdgpu_dm_trigger_timing_sync(struct drm_device *dev);
 #define MAX_COLOR_LEGACY_LUT_ENTRIES 256
 
 void amdgpu_dm_init_color_mod(void);
+int amdgpu_dm_verify_lut_sizes(const struct drm_crtc_state *crtc_state);
 int amdgpu_dm_update_crtc_color_mgmt(struct dm_crtc_state *crtc);
 int amdgpu_dm_update_plane_color_mgmt(struct dm_crtc_state *crtc,
 				      struct dc_plane_state *dc_plane_state);

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c

@@ -284,6 +284,37 @@ static int __set_input_tf(struct dc_transfer_func *func,
 	return res ? 0 : -ENOMEM;
 }
 
+/**
+ * Verifies that the Degamma and Gamma LUTs attached to the |crtc_state| are of
+ * the expected size.
+ * Returns 0 on success.
+ */
+int amdgpu_dm_verify_lut_sizes(const struct drm_crtc_state *crtc_state)
+{
+	const struct drm_color_lut *lut = NULL;
+	uint32_t size = 0;
+
+	lut = __extract_blob_lut(crtc_state->degamma_lut, &size);
+	if (lut && size != MAX_COLOR_LUT_ENTRIES) {
+		DRM_DEBUG_DRIVER(
+			"Invalid Degamma LUT size. Should be %u but got %u.\n",
+			MAX_COLOR_LUT_ENTRIES, size);
+		return -EINVAL;
+	}
+
+	lut = __extract_blob_lut(crtc_state->gamma_lut, &size);
+	if (lut && size != MAX_COLOR_LUT_ENTRIES &&
+	    size != MAX_COLOR_LEGACY_LUT_ENTRIES) {
+		DRM_DEBUG_DRIVER(
+			"Invalid Gamma LUT size. Should be %u (or %u for legacy) but got %u.\n",
+			MAX_COLOR_LUT_ENTRIES, MAX_COLOR_LEGACY_LUT_ENTRIES,
+			size);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 /**
  * amdgpu_dm_update_crtc_color_mgmt: Maps DRM color management to DC stream.
  * @crtc: amdgpu_dm crtc state
@@ -317,14 +348,12 @@ int amdgpu_dm_update_crtc_color_mgmt(struct dm_crtc_state *crtc)
 	bool is_legacy;
 	int r;
 
-	degamma_lut = __extract_blob_lut(crtc->base.degamma_lut, &degamma_size);
-	if (degamma_lut && degamma_size != MAX_COLOR_LUT_ENTRIES)
-		return -EINVAL;
+	r = amdgpu_dm_verify_lut_sizes(&crtc->base);
+	if (r)
+		return r;
 
+	degamma_lut = __extract_blob_lut(crtc->base.degamma_lut, &degamma_size);
 	regamma_lut = __extract_blob_lut(crtc->base.gamma_lut, &regamma_size);
-	if (regamma_lut && regamma_size != MAX_COLOR_LUT_ENTRIES &&
-	    regamma_size != MAX_COLOR_LEGACY_LUT_ENTRIES)
-		return -EINVAL;
 
 	has_degamma =
 		degamma_lut && !__is_lut_linear(degamma_lut, degamma_size);