From 7105f658189c1971f3a2c0cf039722df11770c27 Mon Sep 17 00:00:00 2001
From: Kevin Chyn <kchyn@google.com>
Date: Fri, 30 Oct 2020 16:28:38 -0700
Subject: [PATCH] Add null check before invoking onChallengeInterruptFinished

It's possible that the previous client's owner has died (binderDied),
which results in ClientMonitor clearing the listener.

Fixes: 171189072
Test: Start enrollment, kill settings, enter device credential.
      No crash observed.
Change-Id: I09f5d206b1641e7c4bc1cb0b8ec22045e9c9d35f
---
 .../server/biometrics/sensors/face/Face10.java   | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/services/core/java/com/android/server/biometrics/sensors/face/Face10.java b/services/core/java/com/android/server/biometrics/sensors/face/Face10.java
index f7998ee8caebb..d67ea1687595b 100644
--- a/services/core/java/com/android/server/biometrics/sensors/face/Face10.java
+++ b/services/core/java/com/android/server/biometrics/sensors/face/Face10.java
@@ -582,13 +582,19 @@ class Face10 implements IHwBinder.DeathRecipient {
                     final FaceGenerateChallengeClient previousChallengeOwner =
                             mCurrentChallengeOwner.getInterruptedClient();
                     mCurrentChallengeOwner = null;
+
                     Slog.d(TAG, "Previous challenge owner: " + previousChallengeOwner);
                     if (previousChallengeOwner != null) {
-                        try {
-                            previousChallengeOwner.getListener()
-                                    .onChallengeInterruptFinished(mSensorId);
-                        } catch (RemoteException e) {
-                            Slog.e(TAG, "Unable to notify interrupt finished", e);
+                        final ClientMonitorCallbackConverter listener =
+                                previousChallengeOwner.getListener();
+                        if (listener == null) {
+                            Slog.w(TAG, "Listener is null");
+                        } else {
+                            try {
+                                listener.onChallengeInterruptFinished(mSensorId);
+                            } catch (RemoteException e) {
+                                Slog.e(TAG, "Unable to notify interrupt finished", e);
+                            }
                         }
                     }
                 }