Guard against null image data in CJBig2_GRRDProc.

core/src/fxcodec/jbig2/JBig2_GeneralDecoder.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_GeneralDecoder.h"
 #include "JBig2_ArithDecoder.h"
 #include "JBig2_ArithIntDecoder.h"
 #include "JBig2_HuffmanDecoder.h"
@@ skipping 701 matching lines @@
                                        h - GRREFERENCEDY + 1)) &
                 0x07;
       }
     }
   }
   return GRREG;
 }
 CJBig2_Image* CJBig2_GRRDProc::decode_Template0_opt(
     CJBig2_ArithDecoder* pArithDecoder,
     JBig2ArithCtx* grContext) {
+  if (!GRREFERENCE->m_pData)
+    return nullptr;
+
   FX_BOOL LTP, SLTP, bVal;
   FX_DWORD CONTEXT;
   FX_DWORD line1, line1_r, line2_r, line3_r;
   uint8_t *pLine, *pLineR, cVal;
   intptr_t nStride, nStrideR, nOffset;
   int32_t k, nBits;
   int32_t GRWR, GRHR;
   int32_t GRW, GRH;
   GRW = (int32_t)CJBig2_GRRDProc::GRW;
   GRH = (int32_t)CJBig2_GRRDProc::GRH;
@@ skipping 214 matching lines @@
                                        h - GRREFERENCEDY + 1)) &
                 0x03;
       }
     }
   }
   return GRREG;
 }
 CJBig2_Image* CJBig2_GRRDProc::decode_Template1_opt(
     CJBig2_ArithDecoder* pArithDecoder,
     JBig2ArithCtx* grContext) {
+  if (!GRREFERENCE->m_pData)
+    return nullptr;
+
   FX_BOOL LTP, SLTP, bVal;
   FX_DWORD CONTEXT;
   FX_DWORD line1, line1_r, line2_r, line3_r;
   uint8_t *pLine, *pLineR, cVal;
   intptr_t nStride, nStrideR, nOffset;
   int32_t k, nBits;
   int32_t GRWR, GRHR;
   int32_t GRW, GRH;
   GRW = (int32_t)CJBig2_GRRDProc::GRW;
   GRH = (int32_t)CJBig2_GRRDProc::GRH;
@@ skipping 2249 matching lines @@
     }
     if (pPause && pPause->NeedToPauseNow()) {
       m_loopIndex++;
       m_ProssiveStatus = FXCODEC_STATUS_DECODE_TOBECONTINUE;
       return FXCODEC_STATUS_DECODE_TOBECONTINUE;
     }
   }
   m_ProssiveStatus = FXCODEC_STATUS_DECODE_FINISH;
   return FXCODEC_STATUS_DECODE_FINISH;
 }