Fix unninitialized 'tmp' in CJBig2_Image::composeTo_opt2

core/src/fxcodec/jbig2/JBig2_Image.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
  
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "JBig2_Image.h"
 #include "../../../include/fxcrt/fx_basic.h"
 #include "../../../include/fxcrt/fx_coordinates.h"
 #include <limits.h>
@@ skipping 758 matching lines @@
         return;
     }
     m_pData = (FX_BYTE*)m_pModule->JBig2_Realloc(m_pData, h * m_nStride);
     if(h > m_nHeight) {
         JBIG2_memset(m_pData + m_nHeight * m_nStride, v ? 0xff : 0, (h - m_nHeight)*m_nStride);
     }
     m_nHeight = h;
 }
 FX_BOOL CJBig2_Image::composeTo_opt2(CJBig2_Image *pDst, FX_INT32 x, FX_INT32 y, JBig2ComposeOp op)
 {
-    FX_INT32 xs0, ys0, xs1, ys1, xd0, yd0, xd1, yd1, xx, yy, w, h, middleDwords, lineLeft;
-    FX_DWORD s1, d1, d2, shift, shift1, shift2, tmp, tmp1, tmp2, maskL, maskR, maskM;
-    FX_BYTE *lineSrc, *lineDst, *sp, *dp;
+    FX_INT32 xs0 = 0, ys0  = 0, xs1  = 0, ys1   = 0, xd0    = 0, yd0          = 0, xd1      = 0, 
+             yd1 = 0, xx   = 0, yy   = 0, w     = 0, h      = 0, middleDwords = 0, lineLeft = 0;
+
+    FX_DWORD s1  = 0, d1   = 0, d2   = 0, shift = 0, shift1 = 0, shift2       = 0, 
+             tmp = 0, tmp1 = 0, tmp2 = 0, maskL = 0, maskR  = 0, maskM        = 0;
+
+    FX_BYTE *lineSrc = NULL, *lineDst = NULL, *sp = NULL, *dp = NULL;
+
     if (!m_pData) {
         return FALSE;
     }
     if (x < -1048576 || x > 1048576 || y < -1048576 || y > 1048576) {
         return FALSE;
     }
     if(y < 0) {
         ys0 = -y;
     } else {

[Tom Sepez, 2014/08/04 17:58:22]

can we remove some of these   else { ys0 = 0 } branches if we're setting them
all to zero above?  Alternatively, can we keep the branches and figure out which
ones need to be initialized vs. which ones dont?

         ys0 = 0;
     }
     if(y + m_nHeight > pDst->m_nHeight) {
         ys1 = pDst->m_nHeight - y;
     } else {
         ys1 = m_nHeight;
     }
     if(x < 0) {
         xs0 = -x;
     } else {
@@ skipping 809 matching lines @@
                     dp[2] = (FX_BYTE)(tmp >> 8);
                     dp[3] = (FX_BYTE)tmp;
                 }
                 lineSrc += m_nStride;
                 lineDst += pDst->m_nStride;
             }
         }
     }
     return 1;
 }