Introduce CFX_UnownedPtr to detect lifetime inversion issues.

There are places where an object "child" has a raw pointer
back to object "owner" with the understanding that owner will
always outlive child.

Violating this constraint can lead to use after free, but this
requires finding two paths: one that frees the objects in the
wrong order, and one that uses the object after the free. The
purpose of this patch is to detect the constraint violation
even when the second path is not hit.

We create a template that is used in place of TYPE*. It's dtor,
when a memory tool is present, goes out and probes the first
byte of the object to which it points.  Used in "child", this
allows the memory tool to prove that the "owner" is still alive
at the time the child is destroyed, and hence the constraint is
never violated.

Change-Id: I2a6d696d51dda4a79ee2f00a6752965e058a6417
Reviewed-on: https://pdfium-review.googlesource.com/5475
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>

9 files changed, 27 insertions, 18 deletions

diff --git a/xfa/fwl/cfwl_caret.cpp b/xfa/fwl/cfwl_caret.cpp
index a6ea9ddb56..21387a47f9 100644
--- a/xfa/fwl/cfwl_caret.cpp
+++ b/xfa/fwl/cfwl_caret.cpp
@@ -97,7 +97,7 @@ void CFWL_Caret::OnDrawWidget(CFX_Graphics* pGraphics,
 CFWL_Caret::Timer::Timer(CFWL_Caret* pCaret) : CFWL_Timer(pCaret) {}
 
 void CFWL_Caret::Timer::Run(CFWL_TimerInfo* pTimerInfo) {
-  CFWL_Caret* pCaret = static_cast<CFWL_Caret*>(m_pWidget);
+  CFWL_Caret* pCaret = static_cast<CFWL_Caret*>(m_pWidget.Get());
   if (!(pCaret->GetStates() & FWL_STATE_CAT_HightLight))
     pCaret->SetStates(FWL_STATE_CAT_HightLight);
   else
diff --git a/xfa/fwl/cfwl_caret.h b/xfa/fwl/cfwl_caret.h
index e0c07d301a..da0548c2bf 100644
--- a/xfa/fwl/cfwl_caret.h
+++ b/xfa/fwl/cfwl_caret.h
@@ -51,7 +51,7 @@ class CFWL_Caret : public CFWL_Widget {
                    const CFX_Matrix* pMatrix);
 
   std::unique_ptr<CFWL_Caret::Timer> m_pTimer;
-  CFWL_TimerInfo* m_pTimerInfo;  // not owned.
+  CFX_UnownedPtr<CFWL_TimerInfo> m_pTimerInfo;
 };
 
 #endif  // XFA_FWL_CFWL_CARET_H_
diff --git a/xfa/fwl/cfwl_scrollbar.cpp b/xfa/fwl/cfwl_scrollbar.cpp
index 72797ed315..79e8b48115 100644
--- a/xfa/fwl/cfwl_scrollbar.cpp
+++ b/xfa/fwl/cfwl_scrollbar.cpp
@@ -485,8 +485,7 @@ void CFWL_ScrollBar::DoMouseHover(int32_t iItem,
 CFWL_ScrollBar::Timer::Timer(CFWL_ScrollBar* pToolTip) : CFWL_Timer(pToolTip) {}
 
 void CFWL_ScrollBar::Timer::Run(CFWL_TimerInfo* pTimerInfo) {
-  CFWL_ScrollBar* pButton = static_cast<CFWL_ScrollBar*>(m_pWidget);
-
+  CFWL_ScrollBar* pButton = static_cast<CFWL_ScrollBar*>(m_pWidget.Get());
   if (pButton->m_pTimerInfo)
     pButton->m_pTimerInfo->StopTimer();
 
diff --git a/xfa/fwl/cfwl_spinbutton.cpp b/xfa/fwl/cfwl_spinbutton.cpp
index 6e58b69baf..65bd6cdd3a 100644
--- a/xfa/fwl/cfwl_spinbutton.cpp
+++ b/xfa/fwl/cfwl_spinbutton.cpp
@@ -336,7 +336,6 @@ void CFWL_SpinButton::OnKeyDown(CFWL_MessageKey* pMsg) {
 
   CFWL_Event wmPosChanged(CFWL_Event::Type::Click, this);
   DispatchEvent(&wmPosChanged);
-
   RepaintRect(bUpEnable ? m_rtUpButton : m_rtDnButton);
 }
 
@@ -344,8 +343,7 @@ CFWL_SpinButton::Timer::Timer(CFWL_SpinButton* pToolTip)
     : CFWL_Timer(pToolTip) {}
 
 void CFWL_SpinButton::Timer::Run(CFWL_TimerInfo* pTimerInfo) {
-  CFWL_SpinButton* pButton = static_cast<CFWL_SpinButton*>(m_pWidget);
-
+  CFWL_SpinButton* pButton = static_cast<CFWL_SpinButton*>(m_pWidget.Get());
   if (!pButton->m_pTimerInfo)
     return;
 
diff --git a/xfa/fwl/cfwl_timer.cpp b/xfa/fwl/cfwl_timer.cpp
index 0cd3b2b768..2734e49d78 100644
--- a/xfa/fwl/cfwl_timer.cpp
+++ b/xfa/fwl/cfwl_timer.cpp
@@ -12,6 +12,10 @@
 #include "xfa/fwl/ifwl_adaptertimermgr.h"
 #include "xfa/fxfa/cxfa_ffapp.h"
 
+CFWL_Timer::CFWL_Timer(CFWL_Widget* parent) : m_pWidget(parent) {}
+
+CFWL_Timer::~CFWL_Timer() {}
+
 CFWL_TimerInfo* CFWL_Timer::StartTimer(uint32_t dwElapse, bool bImmediately) {
   const CFWL_App* pApp = m_pWidget->GetOwnerApp();
   if (!pApp)
diff --git a/xfa/fwl/cfwl_timer.h b/xfa/fwl/cfwl_timer.h
index 6c9079acfe..93de009ed1 100644
--- a/xfa/fwl/cfwl_timer.h
+++ b/xfa/fwl/cfwl_timer.h
@@ -7,6 +7,7 @@
 #ifndef XFA_FWL_CFWL_TIMER_H_
 #define XFA_FWL_CFWL_TIMER_H_
 
+#include "core/fxcrt/cfx_unowned_ptr.h"
 #include "core/fxcrt/fx_system.h"
 
 class CFWL_TimerInfo;
@@ -14,14 +15,14 @@ class CFWL_Widget;
 
 class CFWL_Timer {
  public:
-  explicit CFWL_Timer(CFWL_Widget* parent) : m_pWidget(parent) {}
-  virtual ~CFWL_Timer() {}
+  explicit CFWL_Timer(CFWL_Widget* parent);
+  virtual ~CFWL_Timer();
 
   virtual void Run(CFWL_TimerInfo* hTimer) = 0;
   CFWL_TimerInfo* StartTimer(uint32_t dwElapse, bool bImmediately);
 
  protected:
-  CFWL_Widget* m_pWidget;  // Not owned.
+  CFX_UnownedPtr<CFWL_Widget> m_pWidget;
 };
 
 #endif  // XFA_FWL_CFWL_TIMER_H_
diff --git a/xfa/fwl/cfwl_timerinfo.cpp b/xfa/fwl/cfwl_timerinfo.cpp
index 8c7aaebbbb..ee4746af3f 100644
--- a/xfa/fwl/cfwl_timerinfo.cpp
+++ b/xfa/fwl/cfwl_timerinfo.cpp
@@ -8,6 +8,12 @@
 
 #include "xfa/fwl/ifwl_adaptertimermgr.h"
 
+CFWL_TimerInfo::CFWL_TimerInfo(IFWL_AdapterTimerMgr* mgr) : m_pMgr(mgr) {
+  ASSERT(mgr);
+}
+
+CFWL_TimerInfo::~CFWL_TimerInfo() {}
+
 void CFWL_TimerInfo::StopTimer() {
   m_pMgr->Stop(this);
 }
diff --git a/xfa/fwl/cfwl_timerinfo.h b/xfa/fwl/cfwl_timerinfo.h
index a47fede60f..ae77ef5d59 100644
--- a/xfa/fwl/cfwl_timerinfo.h
+++ b/xfa/fwl/cfwl_timerinfo.h
@@ -7,21 +7,20 @@
 #ifndef XFA_FWL_CFWL_TIMERINFO_H_
 #define XFA_FWL_CFWL_TIMERINFO_H_
 
+#include "core/fxcrt/cfx_unowned_ptr.h"
 #include "core/fxcrt/fx_system.h"
 
 class IFWL_AdapterTimerMgr;
 
 class CFWL_TimerInfo {
  public:
-  explicit CFWL_TimerInfo(IFWL_AdapterTimerMgr* mgr) : m_pMgr(mgr) {
-    ASSERT(mgr);
-  }
-  virtual ~CFWL_TimerInfo() {}
+  explicit CFWL_TimerInfo(IFWL_AdapterTimerMgr* mgr);
+  virtual ~CFWL_TimerInfo();
 
   void StopTimer();
 
  private:
-  IFWL_AdapterTimerMgr* m_pMgr;  // Not owned.
+  CFX_UnownedPtr<IFWL_AdapterTimerMgr> m_pMgr;
 };
 
 #endif  // XFA_FWL_CFWL_TIMERINFO_H_
diff --git a/xfa/fwl/cfwl_widget.h b/xfa/fwl/cfwl_widget.h
index b556e7a424..dd8fb5654b 100644
--- a/xfa/fwl/cfwl_widget.h
+++ b/xfa/fwl/cfwl_widget.h
@@ -6,8 +6,10 @@
 
 #ifndef XFA_FWL_CFWL_WIDGET_H_
 #define XFA_FWL_CFWL_WIDGET_H_
+
 #include <memory>
 
+#include "core/fxcrt/cfx_unowned_ptr.h"
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxcrt/fx_system.h"
 #include "xfa/fwl/cfwl_event.h"
@@ -96,10 +98,10 @@ class CFWL_Widget : public IFWL_WidgetDelegate {
 
   void SetDelegate(IFWL_WidgetDelegate* delegate) { m_pDelegate = delegate; }
   IFWL_WidgetDelegate* GetDelegate() {
-    return m_pDelegate ? m_pDelegate : this;
+    return m_pDelegate ? m_pDelegate.Get() : this;
   }
   const IFWL_WidgetDelegate* GetDelegate() const {
-    return m_pDelegate ? m_pDelegate : this;
+    return m_pDelegate ? m_pDelegate.Get() : this;
   }
 
   const CFWL_App* GetOwnerApp() const { return m_pOwnerApp; }
@@ -182,7 +184,7 @@ class CFWL_Widget : public IFWL_WidgetDelegate {
 
   CXFA_FFWidget* m_pLayoutItem;
   uint32_t m_nEventKey;
-  IFWL_WidgetDelegate* m_pDelegate;  // Not owned.
+  CFX_UnownedPtr<IFWL_WidgetDelegate> m_pDelegate;
 };
 
 #endif  // XFA_FWL_CFWL_WIDGET_H_