From 4cf6809d7583c134d38f2aa5883abdbac06b32e9 Mon Sep 17 00:00:00 2001
From: Patrick Rohr <prohr@google.com>
Date: Fri, 20 Aug 2021 07:56:26 +0200
Subject: [PATCH] prevent nullptr dereference when calling unwanted

When the EthernetNetworkAgent has already been stopped, a call to
unwanted will cause a crash due to a nullptr derefernce.

Bug: 197279734
Test: atest EthernetNetworkFactoryTest
Change-Id: Ice39c603bdd3e3139aa8ece7fb897bf7b567e74b
---
 .../android/server/ethernet/EthernetNetworkFactory.java    | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/service-t/src/com/android/server/ethernet/EthernetNetworkFactory.java b/service-t/src/com/android/server/ethernet/EthernetNetworkFactory.java
index 32dbd7e0b6..cd086e721f 100644
--- a/service-t/src/com/android/server/ethernet/EthernetNetworkFactory.java
+++ b/service-t/src/com/android/server/ethernet/EthernetNetworkFactory.java
@@ -506,12 +506,15 @@ public class EthernetNetworkFactory extends NetworkFactory {
                     mNetworkFactory.getProvider(), new EthernetNetworkAgent.Callbacks() {
                         @Override
                         public void onNetworkUnwanted() {
+                            // if mNetworkAgent is null, we have already called stop.
+                            if (mNetworkAgent == null) return;
+
                             if (this == mNetworkAgent.getCallbacks()) {
                                 stop();
-                            } else if (mNetworkAgent != null) {
+                            } else {
                                 Log.d(TAG, "Ignoring unwanted as we have a more modern " +
                                         "instance");
-                            }  // Otherwise, we've already called stop.
+                            }
                         }
                     });
             mNetworkAgent.register();