From 1aeca095d380c3cef633d7f97588bc04000f3496 Mon Sep 17 00:00:00 2001
From: Robin Lee <rgl@google.com>
Date: Mon, 11 Dec 2017 18:24:03 +0100
Subject: [PATCH] Handle getActiveAdmins() == null safely.

Test: adb install -r $OUT/system/priv-app/Settings/Settings.apk && adb shell am start -n com.android.settings/.DeviceAdminAdd --es android.app.extra.DEVICE_ADMIN_PACKAGE_NAME com.example.nonexistent
Change-Id: I1e3cf406e8053f6dbf99669f33b7c16648c9c8f8
Fix: 70491813
---
 src/com/android/settings/DeviceAdminAdd.java | 25 +++++++++++++-------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/src/com/android/settings/DeviceAdminAdd.java b/src/com/android/settings/DeviceAdminAdd.java
index 2fd769b42a2..0ad882df9a2 100644
--- a/src/com/android/settings/DeviceAdminAdd.java
+++ b/src/com/android/settings/DeviceAdminAdd.java
@@ -69,6 +69,7 @@ import org.xmlpull.v1.XmlPullParserException;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Optional;
 
 public class DeviceAdminAdd extends Activity {
     static final String TAG = "DeviceAdminAdd";
@@ -145,18 +146,14 @@ public class DeviceAdminAdd extends Activity {
                 DevicePolicyManager.EXTRA_DEVICE_ADMIN);
         if (who == null) {
             String packageName = getIntent().getStringExtra(EXTRA_DEVICE_ADMIN_PACKAGE_NAME);
-            for (ComponentName component : mDPM.getActiveAdmins()) {
-                if (component.getPackageName().equals(packageName)) {
-                    who = component;
-                    mUninstalling = true;
-                    break;
-                }
-            }
-            if (who == null) {
+            Optional<ComponentName> installedAdmin = findAdminWithPackageName(packageName);
+            if (!installedAdmin.isPresent()) {
                 Log.w(TAG, "No component specified in " + action);
                 finish();
                 return;
             }
+            who = installedAdmin.get();
+            mUninstalling = true;
         }
 
         if (action != null && action.equals(DevicePolicyManager.ACTION_SET_PROFILE_OWNER)) {
@@ -692,6 +689,18 @@ public class DeviceAdminAdd extends Activity {
         return info != null ? info.isManagedProfile() : false;
     }
 
+    /**
+     * @return an {@link Optional} containing the admin with a given package name, if it exists,
+     *         or {@link Optional#empty()} otherwise.
+     */
+    private Optional<ComponentName> findAdminWithPackageName(String packageName) {
+        List<ComponentName> admins = mDPM.getActiveAdmins();
+        if (admins == null) {
+            return Optional.empty();
+        }
+        return admins.stream().filter(i -> i.getPackageName().equals(packageName)).findAny();
+    }
+
     private boolean isAdminUninstallable() {
         // System apps can't be uninstalled.
         return !mDeviceAdmin.getActivityInfo().applicationInfo.isSystemApp();