From ec65e54a90f10e9afa4393eea10392b36b7f0ef0 Mon Sep 17 00:00:00 2001
From: Nathan Harold <nharold@google.com>
Date: Thu, 18 Aug 2022 18:39:31 -0700
Subject: Ensure that onCellInfo is always NonNull

During phone creation and phone count changes,
it was possible to get a null value for onCellInfo().

Since the API is documented as NonNull, always return
a non-null value, forcing an empty list in case there
is still a null lurking somewhere else.

Bug: 237964039
Test: atest TelephonyRegistryTest#testCellInfoChanged
Change-Id: I3b46c211f5542a39187b9d3b137f8483c44ccd39
---
 .../core/java/com/android/server/TelephonyRegistry.java   | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/services/core/java/com/android/server/TelephonyRegistry.java b/services/core/java/com/android/server/TelephonyRegistry.java
index 0807fbaf7cc3..1bf1c9faaacc 100644
--- a/services/core/java/com/android/server/TelephonyRegistry.java
+++ b/services/core/java/com/android/server/TelephonyRegistry.java
@@ -339,7 +339,7 @@ public class TelephonyRegistry extends ITelephonyRegistry.Stub {
 
     private int[] mDataConnectionNetworkType;
 
-    private ArrayList<List<CellInfo>> mCellInfo = null;
+    private ArrayList<List<CellInfo>> mCellInfo;
 
     private Map<Integer, List<EmergencyNumber>> mEmergencyNumberList;
 
@@ -725,7 +725,7 @@ public class TelephonyRegistry extends ITelephonyRegistry.Stub {
                 mMessageWaiting[i] = false;
                 mCallForwarding[i] = false;
                 mCellIdentity[i] = null;
-                mCellInfo.add(i, null);
+                mCellInfo.add(i, Collections.EMPTY_LIST);
                 mImsReasonInfo.add(i, null);
                 mSrvccState[i] = TelephonyManager.SRVCC_STATE_HANDOVER_NONE;
                 mCallDisconnectCause[i] = DisconnectCause.NOT_VALID;
@@ -802,7 +802,7 @@ public class TelephonyRegistry extends ITelephonyRegistry.Stub {
         mCallNetworkType = new int[numPhones];
         mCallAttributes = new CallAttributes[numPhones];
         mPreciseDataConnectionStates = new ArrayList<>();
-        mCellInfo = new ArrayList<>();
+        mCellInfo = new ArrayList<>(numPhones);
         mImsReasonInfo = new ArrayList<>();
         mEmergencyNumberList = new HashMap<>();
         mOutgoingCallEmergencyNumber = new EmergencyNumber[numPhones];
@@ -832,7 +832,7 @@ public class TelephonyRegistry extends ITelephonyRegistry.Stub {
             mMessageWaiting[i] =  false;
             mCallForwarding[i] =  false;
             mCellIdentity[i] = null;
-            mCellInfo.add(i, null);
+            mCellInfo.add(i, Collections.EMPTY_LIST);
             mImsReasonInfo.add(i, null);
             mSrvccState[i] = TelephonyManager.SRVCC_STATE_HANDOVER_NONE;
             mCallDisconnectCause[i] = DisconnectCause.NOT_VALID;
@@ -1794,10 +1794,17 @@ public class TelephonyRegistry extends ITelephonyRegistry.Stub {
         if (!checkNotifyPermission("notifyCellInfoForSubscriber()")) {
             return;
         }
+
         if (VDBG) {
             log("notifyCellInfoForSubscriber: subId=" + subId
                 + " cellInfo=" + cellInfo);
         }
+
+        if (cellInfo == null) {
+            loge("notifyCellInfoForSubscriber() received a null list");
+            cellInfo = Collections.EMPTY_LIST;
+        }
+
         int phoneId = getPhoneIdFromSubId(subId);
         synchronized (mRecords) {
             if (validatePhoneId(phoneId)) {
-- 
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