From 8d65db32eba568be3df36247e02ee32f5284e89a Mon Sep 17 00:00:00 2001
From: Bernie Innocenti <codewiz@google.com>
Date: Wed, 9 May 2018 17:58:50 +0900
Subject: [PATCH] Disable APF memory clear on pre-APFv4 devices

Fixes a system crash on HU when connecting to a wifi AP.

Change-Id: I8b71323985b6c5fc8a75f99470c9f86343d57f90
Bug: 78905546
Test: manually on android auto device
---
 services/net/java/android/net/apf/ApfFilter.java | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/services/net/java/android/net/apf/ApfFilter.java b/services/net/java/android/net/apf/ApfFilter.java
index 2bf6e92f26a8e..a7209a076461a 100644
--- a/services/net/java/android/net/apf/ApfFilter.java
+++ b/services/net/java/android/net/apf/ApfFilter.java
@@ -429,9 +429,13 @@ public class ApfFilter {
         try {
             mHardwareAddress = mInterfaceParams.macAddr.toByteArray();
             synchronized(this) {
-                // Clear APF memory.
-                byte[] zeroes = new byte[mApfCapabilities.maximumApfProgramSize];
-                mIpClientCallback.installPacketFilter(zeroes);
+                // Clear the APF memory to reset all counters upon connecting to the first AP
+                // in an SSID. This is limited to APFv4 devices because this large write triggers
+                // a crash on some older devices (b/78905546).
+                if (mApfCapabilities.hasDataAccess()) {
+                    byte[] zeroes = new byte[mApfCapabilities.maximumApfProgramSize];
+                    mIpClientCallback.installPacketFilter(zeroes);
+                }
 
                 // Install basic filters
                 installNewProgramLocked();