diff --git a/media/libstagefright/codec2/include/C2Param.h b/media/libstagefright/codec2/include/C2Param.h
index 2a8c1b2..9785c87 100644
--- a/media/libstagefright/codec2/include/C2Param.h
+++ b/media/libstagefright/codec2/include/C2Param.h
@@ -397,8 +397,8 @@
 
     /// safe(r) type cast from pointer and size
     inline static C2Param* From(void *addr, size_t len) {
-        // _mSize must fit into size
-        if (len < sizeof(_mSize) + offsetof(C2Param, _mSize)) {
+        // _mSize must fit into size, but really C2Param must also to be a valid param
+        if (len < sizeof(C2Param)) {
             return nullptr;
         }
         // _mSize must match length
@@ -446,7 +446,7 @@
     // if other is the same kind of (valid) param as this, copy it into this and return true.
     // otherwise, do not copy anything, and return false.
     inline bool updateFrom(const C2Param &other) {
-        if (other._mSize == _mSize && other._mIndex == _mIndex && _mSize > 0) {
+        if (other._mSize <= _mSize && other._mIndex == _mIndex && _mSize > 0) {
             memcpy(this, &other, _mSize);
             return true;
         }
@@ -620,6 +620,8 @@
 #endif
 
 private:
+    friend struct _C2ParamInspector;
+
     uint32_t _mOffset; // offset of field
     uint32_t _mSize;   // size of field
 };
@@ -720,6 +722,8 @@
     DEFINE_OTHER_COMPARISON_OPERATORS(C2ParamField)
 
 private:
+    friend struct _C2ParamInspector;
+
     C2Param::Index _mIndex; ///< parameter index
     _C2FieldId _mFieldId;   ///< field identifier
 };
diff --git a/media/libstagefright/codec2/vndk/C2ParamInternal.h b/media/libstagefright/codec2/vndk/C2ParamInternal.h
new file mode 100644
index 0000000..0f3812a
--- /dev/null
+++ b/media/libstagefright/codec2/vndk/C2ParamInternal.h
@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_STAGEFRIGHT_C2PARAM_INTERNAL_H_
+#define ANDROID_STAGEFRIGHT_C2PARAM_INTERNAL_H_
+
+#include <C2Param.h>
+
+namespace android {
+
+struct C2_HIDE _C2ParamInspector {
+   inline static uint32_t getIndex(const C2ParamField &pf) {
+        return pf._mIndex;
+    }
+
+    inline static uint32_t getOffset(const C2ParamField &pf) {
+        return pf._mFieldId._mOffset;
+    }
+
+    inline static uint32_t getSize(const C2ParamField &pf) {
+        return pf._mFieldId._mSize;
+    }
+
+    inline static
+    C2ParamField CreateParamField(C2Param::Index index, uint32_t offset, uint32_t size) {
+        return C2ParamField(index, offset, size);
+    }
+};
+
+}
+
+#endif // ANDROID_STAGEFRIGHT_C2PARAM_INTERNAL_H_
+
diff --git a/media/libstagefright/codec2/vndk/include/util/C2ParamUtils.h b/media/libstagefright/codec2/vndk/include/util/C2ParamUtils.h
index 81c5495..3168248 100644
--- a/media/libstagefright/codec2/vndk/include/util/C2ParamUtils.h
+++ b/media/libstagefright/codec2/vndk/include/util/C2ParamUtils.h
@@ -59,6 +59,7 @@
 
 /// \endcond
 
+#undef DEFINE_C2_ENUM_VALUE_AUTO_HELPER
 #define DEFINE_C2_ENUM_VALUE_AUTO_HELPER(name, type, prefix, ...) \
 template<> C2FieldDescriptor::named_values_type C2FieldDescriptor::namedValuesFor(const name &r __unused) { \
     return C2ParamUtils::sanitizeEnumValues( \
@@ -67,6 +68,7 @@
             prefix); \
 }
 
+#undef DEFINE_C2_ENUM_VALUE_CUSTOM_HELPER
 #define DEFINE_C2_ENUM_VALUE_CUSTOM_HELPER(name, type, names, ...) \
 template<> C2FieldDescriptor::named_values_type C2FieldDescriptor::namedValuesFor(const name &r __unused) { \
     return C2ParamUtils::customEnumValues( \
@@ -260,6 +262,21 @@
         }
         return namedValues;
     }
+
+    /// safe(r) parsing from parameter blob
+    static
+    C2Param *ParseFirst(const uint8_t *blob, size_t size) {
+        // _mSize must fit into size, but really C2Param must also to be a valid param
+        if (size < sizeof(C2Param)) {
+            return nullptr;
+        }
+        // _mSize must match length
+        C2Param *param = (C2Param*)blob;
+        if (param->size() > size) {
+            return nullptr;
+        }
+        return param;
+    }
 };
 
 /* ---------------------------- UTILITIES FOR PARAMETER REFLECTION ---------------------------- */