Adjust the order of clearing resource in CPDF_DocPageData::Clear

core/src/fpdfapi/fpdf_page/fpdf_page_doc.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 "../../../include/fpdfapi/fpdf_page.h"
 #include "../../../include/fpdfapi/fpdf_module.h"
 #include "../../../include/fdrm/fx_crypt.h"
 #include "../fpdf_font/font_int.h"
@@ skipping 133 matching lines @@
     m_FontFileMap.InitHashTable(32);
 }
 CPDF_DocPageData::~CPDF_DocPageData()
 {
     Clear(FALSE);
     Clear(TRUE);
 }
 void CPDF_DocPageData::Clear(FX_BOOL bForceRelease)
 {
     FX_POSITION pos;
-    FX_DWORD    nCount;
 
     m_bForceClear = bForceRelease;
+
+    // Release objects saved in the resource maps like font map and color space map.
+    // The compound objects shall be released before simple ones.
     pos = m_FontMap.GetStartPosition();
     while (pos) {
         CPDF_Dictionary* fontDict;
         CPDF_CountedObject<CPDF_Font*>* fontData;
         m_FontMap.GetNextAssoc(pos, fontDict, fontData);
-        nCount = fontData->m_nCount;
-        if (bForceRelease || nCount < 2) {
+        if (!fontData->m_Obj) {
+            continue;
+        }
+        if (bForceRelease || fontData->m_nCount < 2) {
             delete fontData->m_Obj;
             fontData->m_Obj = NULL;
         }
     }
-    pos = m_ImageMap.GetStartPosition();
-    while (pos) {
-        FX_DWORD objNum;
-        CPDF_CountedObject<CPDF_Image*>* imageData;
-        m_ImageMap.GetNextAssoc(pos, objNum, imageData);
-        nCount = imageData->m_nCount;
-        if (bForceRelease || nCount < 2) {
-            delete imageData->m_Obj;
-            delete imageData;
-            m_ImageMap.RemoveKey(objNum);
-        }
-    }
     pos = m_ColorSpaceMap.GetStartPosition();
     while (pos) {
         CPDF_Object* csKey;
         CPDF_CountedObject<CPDF_ColorSpace*>* csData;
         m_ColorSpaceMap.GetNextAssoc(pos, csKey, csData);
-        nCount = csData->m_nCount;
-        if (bForceRelease || nCount < 2) {
+        if (!csData->m_Obj) {
+            continue;
+        }
+        if (bForceRelease || csData->m_nCount < 2) {
+            // csData->m_Obj is deleted in the function of ReleaseCS().
             csData->m_Obj->ReleaseCS();
             csData->m_Obj = NULL;
         }
     }
     pos = m_IccProfileMap.GetStartPosition();
     while (pos) {
         CPDF_Stream* ipKey;
         CPDF_CountedObject<CPDF_IccProfile*>* ipData;
         m_IccProfileMap.GetNextAssoc(pos, ipKey, ipData);
-        nCount = ipData->m_nCount;
-        if (bForceRelease || nCount < 2) {
+        if (!ipData->m_Obj) {
+            continue;
+        }
+        if (bForceRelease || ipData->m_nCount < 2) {
             FX_POSITION pos2 = m_HashProfileMap.GetStartPosition();
             while (pos2) {
                 CFX_ByteString bsKey;
                 CPDF_Stream* pFindStream = NULL;
                 m_HashProfileMap.GetNextAssoc(pos2, bsKey, (void*&)pFindStream);
                 if (ipKey == pFindStream) {
                     m_HashProfileMap.RemoveKey(bsKey);
                     break;
                 }
             }
             delete ipData->m_Obj;
+            ipData->m_Obj = NULL;
             delete ipData;
             m_IccProfileMap.RemoveKey(ipKey);
         }
     }
     pos = m_FontFileMap.GetStartPosition();
     while (pos) {
         CPDF_Stream* ftKey;
         CPDF_CountedObject<CPDF_StreamAcc*>* ftData;
         m_FontFileMap.GetNextAssoc(pos, ftKey, ftData);
-        nCount = ftData->m_nCount;
-        if (bForceRelease || nCount < 2) {
+        if (!ftData->m_Obj) {
+            continue;
+        }
+        if (bForceRelease || ftData->m_nCount < 2) {
             delete ftData->m_Obj;
+            ftData->m_Obj = NULL;
             delete ftData;
             m_FontFileMap.RemoveKey(ftKey);
         }
     }
     pos = m_PatternMap.GetStartPosition();
     while (pos) {
         CPDF_Object* ptObj;
         CPDF_CountedObject<CPDF_Pattern*>* ptData;
         m_PatternMap.GetNextAssoc(pos, ptObj, ptData);
-        nCount = ptData->m_nCount;
-        if (bForceRelease || nCount < 2) {
+        if (!ptData->m_Obj) {
+            continue;
+        }
+        if (bForceRelease || ptData->m_nCount < 2) {
             ptData->m_Obj->SetForceClear(bForceRelease);
             delete ptData->m_Obj;
             ptData->m_Obj = NULL;
         }
     }
+    pos = m_ImageMap.GetStartPosition();
+    while (pos) {
+        FX_DWORD objNum;
+        CPDF_CountedObject<CPDF_Image*>* imageData;
+        m_ImageMap.GetNextAssoc(pos, objNum, imageData);
+        if (!imageData->m_Obj) {
+            continue;
+        }
+        if (bForceRelease || imageData->m_nCount < 2) {
+            delete imageData->m_Obj;
+            imageData->m_Obj = NULL;
+            delete imageData;
+            m_ImageMap.RemoveKey(objNum);
+        }
+    }
 }
 CPDF_Font* CPDF_DocPageData::GetFont(CPDF_Dictionary* pFontDict, FX_BOOL findOnly)
 {
     if (!pFontDict) {
         return NULL;
     }
     if (findOnly) {
         CPDF_CountedObject<CPDF_Font*>* fontData;
         if (m_FontMap.Lookup(pFontDict, fontData)) {
             if (!fontData->m_Obj) {
@@ skipping 382 matching lines @@
     m_FontFileMap.SetAt(pFontStream, ftData);
     return pFontFile;
 }
 void CPDF_DocPageData::ReleaseFontFileStreamAcc(CPDF_Stream* pFontStream, FX_BOOL bForce)
 {
     if (!pFontStream) {
         return;
     }
     PDF_DocPageData_Release<CPDF_Stream*, CPDF_StreamAcc*>(m_FontFileMap, pFontStream, NULL, bForce);
 }