Enforce that registered authenticators are not null

OEMs should ensure that the config_biometric_sensors
overlay for core/res/res/values.xml is correct. The majority
of devices already have fingerprint sensors, thus to ease
migration, the default configuration is for a "strong
fingerprint sensor on ID0". On devices where this is not true,
the config must be overlaid with whatever sensor the device
actually has.

Bug: 141025588

Test: atest BiometricServiceTest
Change-Id: I61f56d4f11fb7ce3d164a3528a8ecc3522c7e342

2 files changed, 18 insertions, 0 deletions

diff --git a/services/core/java/com/android/server/biometrics/BiometricService.java b/services/core/java/com/android/server/biometrics/BiometricService.java
index 770ea8676ecb..0f51e39d128a 100644
--- a/services/core/java/com/android/server/biometrics/BiometricService.java
+++ b/services/core/java/com/android/server/biometrics/BiometricService.java
@@ -764,6 +764,12 @@ public class BiometricService extends SystemService {
                     + " Modality: " + modality
                     + " Strength: " + strength);
 
+            if (authenticator == null) {
+                throw new IllegalArgumentException("Authenticator must not be null."
+                        + " Did you forget to modify the core/res/res/values/xml overlay for"
+                        + " config_biometric_sensors?");
+            }
+
             if (strength != Authenticators.BIOMETRIC_STRONG
                     && strength != Authenticators.BIOMETRIC_WEAK) {
                 throw new IllegalStateException("Unsupported strength");
diff --git a/services/tests/servicestests/src/com/android/server/biometrics/BiometricServiceTest.java b/services/tests/servicestests/src/com/android/server/biometrics/BiometricServiceTest.java
index 9a2ccef4f3fb..211fc4db6211 100644
--- a/services/tests/servicestests/src/com/android/server/biometrics/BiometricServiceTest.java
+++ b/services/tests/servicestests/src/com/android/server/biometrics/BiometricServiceTest.java
@@ -1177,6 +1177,18 @@ public class BiometricServiceTest {
                 mFingerprintAuthenticator);
     }
 
+    @Test(expected = IllegalArgumentException.class)
+    public void testRegistrationWithNullAuthenticator_throwsIllegalArgumentException()
+            throws Exception {
+        mBiometricService = new BiometricService(mContext, mInjector);
+        mBiometricService.onStart();
+
+        mBiometricService.mImpl.registerAuthenticator(
+                0 /* id */, 2 /* modality */,
+                Authenticators.BIOMETRIC_STRONG /* strength */,
+                null /* authenticator */);
+    }
+
     @Test
     public void testRegistrationHappyPath_isOk() throws Exception {
         // This is being tested in many of the other cases, but here's the base case.