From 5693405bacfc6ae7748e940c37ae0096cb32f45e Mon Sep 17 00:00:00 2001
From: Louis Chang <louischang@google.com>
Date: Thu, 20 Apr 2023 03:29:35 +0000
Subject: [PATCH] Prevents system busy or restarted due to rapid activity
 launch loop

Tracking rapid activity starts. Move the task to back and
kill the app if the rapid launch count exceeds maximum.

Bug: 145096943
Test: verified using a bad app
Change-Id: I164596fb21df55e9daf6d28fb3664e7300eafd7e
---
 .../server/wm/WindowProcessController.java    | 31 +++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/services/core/java/com/android/server/wm/WindowProcessController.java b/services/core/java/com/android/server/wm/WindowProcessController.java
index 85c601fe0a5c7..dbd9e4b8ea68a 100644
--- a/services/core/java/com/android/server/wm/WindowProcessController.java
+++ b/services/core/java/com/android/server/wm/WindowProcessController.java
@@ -107,6 +107,12 @@ public class WindowProcessController extends ConfigurationContainer<Configuratio
     private static final String TAG_RELEASE = TAG + POSTFIX_RELEASE;
     private static final String TAG_CONFIGURATION = TAG + POSTFIX_CONFIGURATION;
 
+    private static final int MAX_RAPID_ACTIVITY_LAUNCH_COUNT = 500;
+    private static final long RAPID_ACTIVITY_LAUNCH_MS = 300;
+    private static final long RESET_RAPID_ACTIVITY_LAUNCH_MS = 5 * RAPID_ACTIVITY_LAUNCH_MS;
+
+    private int mRapidActivityLaunchCount;
+
     // all about the first app in the process
     final ApplicationInfo mInfo;
     final String mName;
@@ -538,7 +544,8 @@ public class WindowProcessController extends ConfigurationContainer<Configuratio
         return mLastActivityLaunchTime > 0;
     }
 
-    void setLastActivityLaunchTime(long launchTime) {
+    void setLastActivityLaunchTime(ActivityRecord r) {
+        long launchTime = r.lastLaunchTime;
         if (launchTime <= mLastActivityLaunchTime) {
             if (launchTime < mLastActivityLaunchTime) {
                 Slog.w(TAG,
@@ -547,9 +554,29 @@ public class WindowProcessController extends ConfigurationContainer<Configuratio
             }
             return;
         }
+        updateRapidActivityLaunch(r, launchTime, mLastActivityLaunchTime);
         mLastActivityLaunchTime = launchTime;
     }
 
+    void updateRapidActivityLaunch(ActivityRecord r, long launchTime, long lastLaunchTime) {
+        if (mInstrumenting || mDebugging || lastLaunchTime <= 0) {
+            return;
+        }
+
+        final long diff = lastLaunchTime - launchTime;
+        if (diff < RAPID_ACTIVITY_LAUNCH_MS) {
+            mRapidActivityLaunchCount++;
+        } else if (diff >= RESET_RAPID_ACTIVITY_LAUNCH_MS) {
+            mRapidActivityLaunchCount = 0;
+        }
+
+        if (mRapidActivityLaunchCount > MAX_RAPID_ACTIVITY_LAUNCH_COUNT) {
+            Slog.w(TAG, "Killing " + mPid + " because of rapid activity launch");
+            r.getRootTask().moveTaskToBack(r.getTask());
+            mAtm.mH.post(() -> mAtm.mAmInternal.killProcess(mName, mUid, "rapidActivityLaunch"));
+        }
+    }
+
     void setLastActivityFinishTimeIfNeeded(long finishTime) {
         if (finishTime <= mLastActivityFinishTime || !hasActivityInVisibleTask()) {
             return;
@@ -696,7 +723,7 @@ public class WindowProcessController extends ConfigurationContainer<Configuratio
 
     void addActivityIfNeeded(ActivityRecord r) {
         // even if we already track this activity, note down that it has been launched
-        setLastActivityLaunchTime(r.lastLaunchTime);
+        setLastActivityLaunchTime(r);
         if (mActivities.contains(r)) {
             return;
         }