drm/i915/guc: Verify hwconfig blob matches supported format

Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>

drivers/gpu/drm/i915/gt/uc/intel_guc_hwconfig.c

@@ -71,6 +71,26 @@ static int guc_hwconfig_discover_size(struct intel_guc_hwconfig *hwconfig)
 	return 0;
 }
 
+static int verify_hwconfig_blob(const struct intel_guc_hwconfig *hwconfig)
+{
+	if (hwconfig->size % 4 != 0 || hwconfig->ptr == NULL)
+		return -EINVAL;
+
+	struct drm_i915_query_hwconfig_blob_item *pos = hwconfig->ptr;
+	u32 remaining = (hwconfig->size / 4);
+	while (remaining > 0) {
+		if (remaining < 2)
+			return -EINVAL;
+		if (pos->length > remaining - 2)
+			return -EINVAL;
+		remaining -= 2 + pos->length;
+		pos = (void *)&pos->data[pos->length];
+	}
+
+	DRM_INFO("hwconfig blob format appears valid\n");
+	return 0;
+}
+
 static int guc_hwconfig_fill_buffer(struct intel_guc_hwconfig *hwconfig)
 {
 	struct intel_guc *guc = hwconfig_to_guc(hwconfig);
@@ -91,6 +111,12 @@ static int guc_hwconfig_fill_buffer(struct intel_guc_hwconfig *hwconfig)
 	if (ret >= 0)
 		memcpy(hwconfig->ptr, vaddr, hwconfig->size);
 
+	if (verify_hwconfig_blob(hwconfig)) {
+		DRM_ERROR("Ignoring invalid hwconfig blob received from "
+			  "GuC!\n");
+		return -EINVAL;
+	}
+
 	i915_vma_unpin_and_release(&vma, I915_VMA_RELEASE_MAP);
 
 	return ret;