Adding a double unlock guard in ProximityAuthBleSystem.

A double call to |screenlock_bridge_->Unlock()| seems to cause a memory
corruption.

BUG=507276

Review URL: https://codereview.chromium.org/1227103005

Cr-Commit-Position: refs/heads/master@{#338454}

2 files changed, 13 insertions, 1 deletions

diff --git a/components/proximity_auth/ble/proximity_auth_ble_system.cc b/components/proximity_auth/ble/proximity_auth_ble_system.cc
index aa3f8da..0ff9653 100644
--- a/components/proximity_auth/ble/proximity_auth_ble_system.cc
+++ b/components/proximity_auth/ble/proximity_auth_ble_system.cc
@@ -93,6 +93,7 @@ ProximityAuthBleSystem::ProximityAuthBleSystem(
       cryptauth_client_factory_(cryptauth_client_factory.Pass()),
       device_whitelist_(new BluetoothLowEnergyDeviceWhitelist(pref_service)),
       device_authenticated_(false),
+      unlock_requested_(false),
       is_polling_screen_state_(false),
       weak_ptr_factory_(this) {
   PA_LOG(INFO) << "Starting Proximity Auth over Bluetooth Low Energy.";
@@ -104,6 +105,7 @@ ProximityAuthBleSystem::ProximityAuthBleSystem(
     ProximityAuthClient* proximity_auth_client)
     : screenlock_bridge_(screenlock_bridge.Pass()),
       proximity_auth_client_(proximity_auth_client),
+      unlock_requested_(false),
       is_polling_screen_state_(false),
       weak_ptr_factory_(this) {
   PA_LOG(INFO) << "Starting Proximity Auth over Bluetooth Low Energy.";
@@ -188,6 +190,7 @@ void ProximityAuthBleSystem::OnScreenDidLock(
       break;
     case ScreenlockBridge::LockHandler::LOCK_SCREEN:
       DCHECK(!connection_finder_);
+      unlock_requested_ = false;
       connection_finder_.reset(CreateConnectionFinder());
       connection_finder_->Find(
           base::Bind(&ProximityAuthBleSystem::OnConnectionFound,
@@ -225,6 +228,7 @@ void ProximityAuthBleSystem::OnScreenDidUnlock(
     device_authenticated_ = false;
   }
 
+  unlock_requested_ = false;
   connection_.reset();
   connection_finder_.reset();
 }
@@ -268,9 +272,10 @@ void ProximityAuthBleSystem::OnMessageReceived(const Connection& connection,
   // Note that this magically unlocks Chrome (no user interaction is needed).
   // This user experience for this operation will be greately improved once
   // the Proximity Auth Unlock Manager migration to C++ is done.
-  if (message.payload() == kScreenUnlocked) {
+  if (message.payload() == kScreenUnlocked && !unlock_requested_) {
     PA_LOG(INFO) << "Device unlocked. Unlock.";
     screenlock_bridge_->Unlock(proximity_auth_client_);
+    unlock_requested_ = true;
   }
 }
 
diff --git a/components/proximity_auth/ble/proximity_auth_ble_system.h b/components/proximity_auth/ble/proximity_auth_ble_system.h
index 34d4b2c..f40c9f2 100644
--- a/components/proximity_auth/ble/proximity_auth_ble_system.h
+++ b/components/proximity_auth/ble/proximity_auth_ble_system.h
@@ -135,8 +135,15 @@ class ProximityAuthBleSystem : public ScreenlockBridge::Observer,
 
   const base::TimeDelta polling_interval_;
 
+  // True if the remote device sent public key contained in |unlock_keyes_| or
+  // |device_whitelist_|.
   bool device_authenticated_;
 
+  // True if the screen is locked and call to |screenlock_bridge_->Unlock()| was
+  // made, but |OnScreenDidUnlock| was not called yet. This is a guard to avoid
+  // a double |screenlock_bridge_->Unlock()| call.
+  bool unlock_requested_;
+
   bool is_polling_screen_state_;
 
   base::WeakPtrFactory<ProximityAuthBleSystem> weak_ptr_factory_;