Initial error handling code

src/effects/SkMergeImageFilter.cpp

 /*
  * Copyright 2012 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkMergeImageFilter.h"
 #include "SkCanvas.h"
 #include "SkDevice.h"
@@ skipping 139 matching lines @@
     buffer.writeBool(fModes != NULL);
     if (fModes) {
         buffer.writeByteArray(fModes, countInputs() * sizeof(fModes[0]));
     }
 }
 
 SkMergeImageFilter::SkMergeImageFilter(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {
     bool hasModes = buffer.readBool();
     if (hasModes) {
         this->initAllocModes();
-        SkASSERT(buffer.getArrayCount() == countInputs() * sizeof(fModes[0]));
+        int nbInputs = countInputs();
+        SkASSERT(buffer.getArrayCount() == nbInputs * sizeof(fModes[0]));
         buffer.readByteArray(fModes);
+        for (int i = 0; i < nbInputs; ++i) {
+            buffer.validateData(SkXfermode::IsValidMode((SkXfermode::Mode)fModes[i]));
+        }
     } else {
         fModes = 0;
     }
 }