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Commit 8e9d78ff authored by Rubin Xu's avatar Rubin Xu
Browse files

Delay gargabe collection during onDestroy() 

Allow the activity object to become unreachable before
iniating a gargabe collection to sanitize memory.

Bug: 189315376
Test: add device lock, confirm device lock in Settings,
      then a memory dump and search for password shards.
Change-Id: I807d74628e1355814807855ad309d86ca1fb38a1
parent cf5bb135

src/com/android/settings/password/ConfirmDeviceCredentialBaseActivity.java

+10 −5
Original line number Original line Diff line number Diff line
@@ -18,6 +18,8 @@ package com.android.settings.password; 




import android.app.KeyguardManager;

import android.app.KeyguardManager;

import android.os.Bundle;

import android.os.Bundle;

import android.os.Handler;

import android.os.Looper;

import android.os.UserManager;

import android.os.UserManager;

import android.util.Log;

import android.util.Log;

import android.view.MenuItem;

import android.view.MenuItem;
@@ -163,11 +165,14 @@ public abstract class ConfirmDeviceCredentialBaseActivity extends SettingsActivi 
    @Override

    @Override

    public void onDestroy() {

    public void onDestroy() {

        super.onDestroy();

        super.onDestroy();

        // Force a garbage collection immediately to remove remnant of user password shards

        // Force a garbage collection to remove remnant of user password shards from memory.

        // from memory.

        // Execute this with a slight delay to allow the activity lifecycle to complete and

        // the instance to become gc-able.

        new Handler(Looper.myLooper()).postDelayed(() -> {

            System.gc();

            System.gc();

            System.runFinalization();

            System.runFinalization();

            System.gc();

            System.gc();

        }, 5000);

    }

    }





    @Override

    @Override

src/com/android/settings/password/ConfirmLockPassword.java

+10 −5
Original line number Original line Diff line number Diff line
@@ -25,6 +25,8 @@ import android.graphics.Typeface; 
import android.os.AsyncTask;

import android.os.AsyncTask;

import android.os.Bundle;

import android.os.Bundle;

import android.os.CountDownTimer;

import android.os.CountDownTimer;

import android.os.Handler;

import android.os.Looper;

import android.os.SystemClock;

import android.os.SystemClock;

import android.os.UserManager;

import android.os.UserManager;

import android.os.storage.StorageManager;

import android.os.storage.StorageManager;
@@ -216,11 +218,14 @@ public class ConfirmLockPassword extends ConfirmDeviceCredentialBaseActivity { 
        public void onDestroy() {

        public void onDestroy() {

            super.onDestroy();

            super.onDestroy();

            mPasswordEntry.setText(null);

            mPasswordEntry.setText(null);

            // Force a garbage collection immediately to remove remnant of user password shards

            // Force a garbage collection to remove remnant of user password shards from memory.

            // from memory.

            // Execute this with a slight delay to allow the activity lifecycle to complete and

            // the instance to become gc-able.

            new Handler(Looper.myLooper()).postDelayed(() -> {

                System.gc();

                System.gc();

                System.runFinalization();

                System.runFinalization();

                System.gc();

                System.gc();

            }, 5000);

        }

        }





        private int getDefaultHeader() {

        private int getDefaultHeader() {