Fix use-after-free on Linux at shutdown

net/base/network_change_notifier_linux.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/base/network_change_notifier_linux.h"
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/threading/thread.h"
 #include "net/base/address_tracker_linux.h"
 #include "net/dns/dns_config_service.h"
 
 namespace net {
 
 class NetworkChangeNotifierLinux::Thread : public base::Thread {
  public:
   explicit Thread(const base::hash_set<std::string>& ignored_interfaces);
   ~Thread() override;
 
   // Plumbing for NetworkChangeNotifier::GetCurrentConnectionType.
   // Safe to call from any thread.
   NetworkChangeNotifier::ConnectionType GetCurrentConnectionType() {
-    return address_tracker_.GetCurrentConnectionType();
+    return address_tracker_->GetCurrentConnectionType();
   }
 
   const internal::AddressTrackerLinux* address_tracker() const {
-    return &address_tracker_;
+    return address_tracker_.get();
   }
 
  protected:
   // base::Thread
   void Init() override;
   void CleanUp() override;
 
  private:
   void OnIPAddressChanged();
   void OnLinkChanged();
   scoped_ptr<DnsConfigService> dns_config_service_;
   // Used to detect online/offline state and IP address changes.
-  internal::AddressTrackerLinux address_tracker_;
+  scoped_ptr<internal::AddressTrackerLinux> address_tracker_;
   NetworkChangeNotifier::ConnectionType last_type_;
 
   DISALLOW_COPY_AND_ASSIGN(Thread);
 };
 
 NetworkChangeNotifierLinux::Thread::Thread(
     const base::hash_set<std::string>& ignored_interfaces)
     : base::Thread("NetworkChangeNotifier"),
-      address_tracker_(
+      address_tracker_(new internal::AddressTrackerLinux(
           base::Bind(&NetworkChangeNotifierLinux::Thread::OnIPAddressChanged,
                      base::Unretained(this)),
           base::Bind(&NetworkChangeNotifierLinux::Thread::OnLinkChanged,
                      base::Unretained(this)),
           base::Bind(base::DoNothing),
-          ignored_interfaces),
+          ignored_interfaces)),
       last_type_(NetworkChangeNotifier::CONNECTION_NONE) {
 }
 
 NetworkChangeNotifierLinux::Thread::~Thread() {
   DCHECK(!Thread::IsRunning());
 }
 
 void NetworkChangeNotifierLinux::Thread::Init() {
-  address_tracker_.Init();
+  address_tracker_->Init();
   dns_config_service_ = DnsConfigService::CreateSystemService();
   dns_config_service_->WatchConfig(
       base::Bind(&NetworkChangeNotifier::SetDnsConfig));
 }
 
 void NetworkChangeNotifierLinux::Thread::CleanUp() {
+  address_tracker_.reset();

[pauljensen, 2016/03/18 18:27:49]

Can you add a comment like:
// Delete AddressTrackerLinux before MessageLoop gets deleted as
// AddressTrackerLinux's FileDescriptorWatcher holds a pointer to the
// MessageLoop.

   dns_config_service_.reset();
 }
 
 void NetworkChangeNotifierLinux::Thread::OnIPAddressChanged() {
   NetworkChangeNotifier::NotifyObserversOfIPAddressChange();
   // When the IP address of a network interface is added/deleted, the
   // connection type may have changed.
   OnLinkChanged();
 }
 
@@ skipping 44 matching lines @@
 NetworkChangeNotifierLinux::GetCurrentConnectionType() const {
   return notifier_thread_->GetCurrentConnectionType();
 }
 
 const internal::AddressTrackerLinux*
 NetworkChangeNotifierLinux::GetAddressTrackerInternal() const {
   return notifier_thread_->address_tracker();
 }
 
 }  // namespace net