SkScaledBitmapSampler: fix memory overwritten

src/images/SkScaledBitmapSampler.cpp

 /*
  * Copyright 2007 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 "SkScaledBitmapSampler.h"
 #include "SkBitmap.h"
@@ skipping 744 matching lines @@
     if (srcYMinusY0 % fDY != 0) {
         // This line is not part of the output, so return false for alpha, since we have
         // not added an alpha to the output.
         return false;
     }
     // Unlike in next(), where the data is used sequentially, this function skips around,
     // so fDstRow and fCurrY are never updated. fDstRow must always be the starting point
     // of the destination bitmap's pixels, which is used to calculate the destination row
     // each time this function is called.
     const int dstY = srcYMinusY0 / fDY;
-    SkASSERT(dstY < fScaledHeight);
+    if (dstY >= fScaledHeight) {
+        return false;
+    }
     char* dstRow = fDstRow + dstY * fDstRowBytes;
     return fRowProc(dstRow, src + fX0 * fSrcPixelSize, fScaledWidth,
                     fDX * fSrcPixelSize, dstY, fCTable);
 }
 
 #ifdef SK_DEBUG
 // The following code is for a test to ensure that changing the method to get the right row proc
 // did not change the row proc unintentionally. Tested by ImageDecodingTest.cpp
 
 // friend of SkScaledBitmapSampler solely for the purpose of accessing fRowProc.
@@ skipping 90 matching lines @@
                     SkScaledBitmapSampler::RowProc actual = RowProcTester::getRowProc(sampler);
                     SkASSERT(expected == actual);
                     procCounter++;
                 }
             }
         }
     }
     SkASSERT(SK_ARRAY_COUNT(gTestProcs) == procCounter);
 }
 #endif // SK_DEBUG