Fix NULL pointer dereference in CPDF_InterForm.

core/src/fpdfdoc/doc_form.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/fpdfdoc/fpdf_doc.h"
 #include "doc_utils.h"
 
 const int nMaxRecursion = 32;
@@ skipping 215 matching lines @@
   _Node *pNode = &m_Root, *pLast = NULL;
   while (nLength > 0 && pNode) {
     pLast = pNode;
     CFX_WideString name = CFX_WideString(pName, nLength);
     pNode = _Lookup(pLast, name);
     name_extractor.GetNext(pName, nLength);
   }
   return pNode;
 }
 CPDF_InterForm::CPDF_InterForm(CPDF_Document* pDocument, FX_BOOL bGenerateAP)
-    : CFX_PrivateData() {
-  m_pDocument = pDocument;
-  m_bGenerateAP = bGenerateAP;
-  m_pFormNotify = NULL;
-  m_bUpdated = FALSE;
-  m_pFieldTree = new CFieldTree;
+    : CFX_PrivateData(),
+      m_pDocument(pDocument),
+      m_bGenerateAP(bGenerateAP),
+      m_pFormDict(nullptr),
+      m_pFieldTree(new CFieldTree),
+      m_pFormNotify(nullptr),
+      m_bUpdated(FALSE) {
   CPDF_Dictionary* pRoot = m_pDocument->GetRoot();
+  if (!pRoot)
+    return;
+
   m_pFormDict = pRoot->GetDict("AcroForm");
-  if (m_pFormDict == NULL) {
+  if (!m_pFormDict)
     return;
-  }
+
   CPDF_Array* pFields = m_pFormDict->GetArray("Fields");
-  if (pFields == NULL) {
+  if (!pFields)
     return;
-  }
+
   int count = pFields->GetCount();
   for (int i = 0; i < count; i++) {
     LoadField(pFields->GetDict(i));
   }
 }
 
 CPDF_InterForm::~CPDF_InterForm() {
   for (auto it : m_ControlMap)
     delete it.second;
-  if (m_pFieldTree) {
-    int nCount = m_pFieldTree->m_Root.CountFields();
-    for (int i = 0; i < nCount; ++i) {
-      delete m_pFieldTree->m_Root.GetField(i);
-    }
-    delete m_pFieldTree;
+
+  int nCount = m_pFieldTree->m_Root.CountFields();
+  for (int i = 0; i < nCount; ++i) {
+    delete m_pFieldTree->m_Root.GetField(i);
   }
 }
 
 FX_BOOL CPDF_InterForm::m_bUpdateAP = TRUE;
 FX_BOOL CPDF_InterForm::UpdatingAPEnabled() {
   return m_bUpdateAP;
 }
 void CPDF_InterForm::EnableUpdateAP(FX_BOOL bUpdateAP) {
   m_bUpdateAP = bUpdateAP;
 }
@@ skipping 1095 matching lines @@
     FDF_ImportField(pField, L"", bNotify);
   }
   if (bNotify && m_pFormNotify != NULL) {
     m_pFormNotify->AfterFormImportData(this);
   }
   return TRUE;
 }
 void CPDF_InterForm::SetFormNotify(const CPDF_FormNotify* pNotify) {
   m_pFormNotify = (CPDF_FormNotify*)pNotify;
 }