Prevent divide by zeros in CJBig2_GSIDProc::decode_MMR().

core/src/fxcodec/jbig2/JBig2_Context.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_Context.h"
 
 #include <list>
 
@@ skipping 1109 matching lines @@
       (m_pStream->read1Byte(&cFlags) != 0) ||
       (m_pStream->readInteger(&pHRD->HGW) != 0) ||
       (m_pStream->readInteger(&pHRD->HGH) != 0) ||
       (m_pStream->readInteger((FX_DWORD*)&pHRD->HGX) != 0) ||
       (m_pStream->readInteger((FX_DWORD*)&pHRD->HGY) != 0) ||
       (m_pStream->readShortInteger(&pHRD->HRX) != 0) ||
       (m_pStream->readShortInteger(&pHRD->HRY) != 0)) {
     nRet = JBIG2_ERROR_TOO_SHORT;
     goto failed;
   }
+  if (pHRD->HGW == 0 || pHRD->HGH == 0) {
+    nRet = JBIG2_ERROR_FATAL;
+    goto failed;
+  }
+
   pHRD->HBW = ri.width;
   pHRD->HBH = ri.height;
   pHRD->HMMR = cFlags & 0x01;
   pHRD->HTEMPLATE = (cFlags >> 1) & 0x03;
   pHRD->HENABLESKIP = (cFlags >> 3) & 0x01;
   pHRD->HCOMBOP = (JBig2ComposeOp)((cFlags >> 4) & 0x07);
   pHRD->HDEFPIXEL = (cFlags >> 7) & 0x01;
   if (pSegment->m_nReferred_to_segment_count != 1) {
     nRet = JBIG2_ERROR_FATAL;
     goto failed;
@@ skipping 427 matching lines @@
         SBSYMCODES[CURTEMP].code = CURCODE;
         CURCODE = CURCODE + 1;
       }
       CURTEMP = CURTEMP + 1;
     }
     CURLEN = CURLEN + 1;
   }
   FX_Free(LENCOUNT);
   FX_Free(FIRSTCODE);
 }