From cd2466ee309bb4d2e88f52e688c0e0e9e5d49b58 Mon Sep 17 00:00:00 2001
From: Adam Bookatz <bookatz@google.com>
Date: Mon, 2 May 2022 12:21:29 -0700
Subject: [PATCH] Ensure getUserName cannot return null

A user can be created with an explicitly null name, as happens in tests.
But getUserName claims to never return null. So we must do a null-check
here to prevent it.

Bug: 227624966
Test: atest UserManagerTest
Change-Id: Iea0e7b6292c6dd49df1bebc5467091a82ddaedb5
---
 core/api/test-current.txt                             |  2 +-
 core/java/android/content/pm/UserInfo.java            |  3 ++-
 core/java/android/os/UserManager.java                 |  5 ++++-
 .../com/android/server/pm/UserManagerService.java     | 11 ++++++++---
 4 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/core/api/test-current.txt b/core/api/test-current.txt
index 4681d49432566..d6a067d35f9b0 100644
--- a/core/api/test-current.txt
+++ b/core/api/test-current.txt
@@ -919,7 +919,7 @@ package android.content.pm {
     field public int id;
     field public String lastLoggedInFingerprint;
     field public long lastLoggedInTime;
-    field public String name;
+    field @Nullable public String name;
     field public boolean partial;
     field public boolean preCreated;
     field public int profileBadge;
diff --git a/core/java/android/content/pm/UserInfo.java b/core/java/android/content/pm/UserInfo.java
index 76e9fcb07f22b..d6e13ac90f828 100644
--- a/core/java/android/content/pm/UserInfo.java
+++ b/core/java/android/content/pm/UserInfo.java
@@ -18,6 +18,7 @@ package android.content.pm;
 
 import android.annotation.IntDef;
 import android.annotation.NonNull;
+import android.annotation.Nullable;
 import android.annotation.TestApi;
 import android.annotation.UserIdInt;
 import android.compat.annotation.UnsupportedAppUsage;
@@ -170,7 +171,7 @@ public class UserInfo implements Parcelable {
     @UnsupportedAppUsage
     public int serialNumber;
     @UnsupportedAppUsage
-    public String name;
+    public @Nullable String name;
     @UnsupportedAppUsage
     public String iconPath;
     @UnsupportedAppUsage
diff --git a/core/java/android/os/UserManager.java b/core/java/android/os/UserManager.java
index a64e63eacd564..196f2f94120e3 100644
--- a/core/java/android/os/UserManager.java
+++ b/core/java/android/os/UserManager.java
@@ -2179,7 +2179,10 @@ public class UserManager {
             }
         } else {
             UserInfo userInfo = getUserInfo(mUserId);
-            return userInfo == null ? "" : userInfo.name;
+            if (userInfo != null && userInfo.name != null) {
+                return userInfo.name;
+            }
+            return "";
         }
     }
 
diff --git a/services/core/java/com/android/server/pm/UserManagerService.java b/services/core/java/com/android/server/pm/UserManagerService.java
index 0dabff8370ba7..bcdf4291ed41a 100644
--- a/services/core/java/com/android/server/pm/UserManagerService.java
+++ b/services/core/java/com/android/server/pm/UserManagerService.java
@@ -1430,6 +1430,8 @@ public class UserManagerService extends IUserManager.Stub {
     /**
      * Returns a UserInfo object with the name filled in, for Owner and Guest, or the original
      * if the name is already set.
+     *
+     * Note: Currently, the resulting name can be null if a user was truly created with a null name.
      */
     private UserInfo userWithName(UserInfo orig) {
         if (orig != null && orig.name == null) {
@@ -1638,7 +1640,7 @@ public class UserManagerService extends IUserManager.Stub {
     }
 
     @Override
-    public String getUserName() {
+    public @NonNull String getUserName() {
         final int callingUid = Binder.getCallingUid();
         if (!hasQueryOrCreateUsersPermission()
                 && !hasPermissionGranted(
@@ -1649,7 +1651,10 @@ public class UserManagerService extends IUserManager.Stub {
         final int userId = UserHandle.getUserId(callingUid);
         synchronized (mUsersLock) {
             UserInfo userInfo = userWithName(getUserInfoLU(userId));
-            return userInfo == null ? "" : userInfo.name;
+            if (userInfo != null && userInfo.name != null) {
+                return userInfo.name;
+            }
+            return "";
         }
     }
 
@@ -4165,7 +4170,7 @@ public class UserManagerService extends IUserManager.Stub {
      * @return the converted user, or {@code null} if no pre-created user could be converted.
      */
     private @Nullable UserInfo convertPreCreatedUserIfPossible(String userType,
-            @UserInfoFlag int flags, String name, @Nullable Object token) {
+            @UserInfoFlag int flags, @Nullable String name, @Nullable Object token) {
         final UserData preCreatedUserData;
         synchronized (mUsersLock) {
             preCreatedUserData = getPreCreatedUserLU(userType);