From 906773a97f1a96e2eeb1758756c86d890e79c6d0 Mon Sep 17 00:00:00 2001
From: Rubin Xu <rubinxu@google.com>
Date: Mon, 9 Aug 2021 17:03:34 +0100
Subject: Attempt to clear memory after keyguard PIN entry

Force object finalization and garbage collection to remove shards
of user PIN from memory.

Bug: 189315376
Test: Unlock keyguard; take ramdump; search for PIN in the dump
Change-Id: I6d951babc225998d959669117c26f823f28fa706
---
 .../src/com/android/keyguard/KeyguardSecurityContainerController.java | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/packages/SystemUI/src/com/android/keyguard/KeyguardSecurityContainerController.java b/packages/SystemUI/src/com/android/keyguard/KeyguardSecurityContainerController.java
index fde8213de0c6..dd7c7ea6b5a5 100644
--- a/packages/SystemUI/src/com/android/keyguard/KeyguardSecurityContainerController.java
+++ b/packages/SystemUI/src/com/android/keyguard/KeyguardSecurityContainerController.java
@@ -146,7 +146,9 @@ public class KeyguardSecurityContainerController extends ViewController<Keyguard
                     try {
                         Thread.sleep(5000);
                     } catch (InterruptedException ignored) { }
-                    Runtime.getRuntime().gc();
+                    System.gc();
+                    System.runFinalization();
+                    System.gc();
                 });
             } else {
                 SysUiStatsLog.write(SysUiStatsLog.KEYGUARD_BOUNCER_PASSWORD_ENTERED,
-- 
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