Fixed a few places where uninitialized memory could have been read

src/effects/SkColorMatrixFilter.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkColorMatrixFilter.h"
 #include "SkColorMatrix.h"
 #include "SkColorPriv.h"
@@ skipping 290 matching lines @@
 
 void SkColorMatrixFilter::flatten(SkFlattenableWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
     SkASSERT(sizeof(fMatrix.fMat)/sizeof(SkScalar) == 20);
     buffer.writeScalarArray(fMatrix.fMat, 20);
 }
 
 SkColorMatrixFilter::SkColorMatrixFilter(SkFlattenableReadBuffer& buffer)
         : INHERITED(buffer) {
     SkASSERT(buffer.getArrayCount() == 20);
-    buffer.readScalarArray(fMatrix.fMat, 20);
-    this->initState(fMatrix.fMat);
-    for (int i = 0; i < 20; ++i) {
-        buffer.validate(SkScalarIsFinite(fMatrix.fMat[i]));

[sugoi1, 2013/12/06 18:39:04]

I didn't find anything obviously wrong with removing the SkScalarIsFinite()
checks after doing some local tests and looking at the uses of fMat in the code.
It does use some arithmetic functions, like operators, min, abs, etc, but there
should be no further consequence to a NaN then turning the result into NaNs. If
these render on the GPU, NaNs may yield an undefined result, depending on the
hardware, but undefined behavior shouldn't cause security issues, hopefully
(maybe I'm wrong).
I don't think these calls had a significant cost (performancewise), though, so I
don't know how much can be gained by removing them, but, for now, I can just let
the fuzzer handle this and try to find issues with this, so that we can at least
know if there's an issue with this.

+    if (buffer.readScalarArray(fMatrix.fMat, 20)) {
+        this->initState(fMatrix.fMat);
     }
 }
 
 bool SkColorMatrixFilter::asColorMatrix(SkScalar matrix[20]) const {
     if (matrix) {
         memcpy(matrix, fMatrix.fMat, 20 * sizeof(SkScalar));
     }
     return true;
 }
 
@@ skipping 164 matching lines @@
     str->append("matrix: (");
     for (int i = 0; i < 20; ++i) {
         str->appendScalar(fMatrix.fMat[i]);
         if (i < 19) {
             str->append(", ");
         }
     }
     str->append(")");
 }
 #endif