From 533c3deb7ba80fd9271748b788d59bfe4631c52f Mon Sep 17 00:00:00 2001
From: Mohammad Samiul Islam <samiul@google.com>
Date: Thu, 15 Oct 2020 01:05:13 +0100
Subject: [PATCH] Prevent extra sessions owned by staged install from living
 across restarts

If system server crashes due to external reasons (not due to
exception in pre-reboot verifications), then the staged install will be
retried. But, any extra sessions that have not been cleaned up will
linger on until removed due to old age.

And if the crash keeps on happening every time at the worst possible
time, then we can have 1024 extra sessions created all with copies of
apks in it. It will waste a lot of user's space.

With this CL, we cleanup any leftover extra sessions whenever system
server is restarted.

Bug: 170784748
Test: manual
Test: verified that without this CL if system server crashses after
extra sessions are created but before they are cleaned up, then folders
start to pile up in /data/app folder with copy of the apks inside.

Change-Id: I5c19093853e28c668f882d37691959b1ac2464cc
Merged-In: I5c19093853e28c668f882d37691959b1ac2464cc
---
 .../com/android/server/pm/PackageInstallerService.java   | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/services/core/java/com/android/server/pm/PackageInstallerService.java b/services/core/java/com/android/server/pm/PackageInstallerService.java
index 1c9d56683dba3..47dc5092c31d3 100644
--- a/services/core/java/com/android/server/pm/PackageInstallerService.java
+++ b/services/core/java/com/android/server/pm/PackageInstallerService.java
@@ -380,6 +380,8 @@ public class PackageInstallerService extends IPackageInstaller.Stub implements
                             Slog.w(TAG, "Abandoning old session created at "
                                         + session.createdMillis);
                             valid = false;
+                        } else if (isExtraSessionForStagedInstall(session)) {
+                            valid = false;
                         } else {
                             valid = true;
                         }
@@ -410,6 +412,13 @@ public class PackageInstallerService extends IPackageInstaller.Stub implements
         }
     }
 
+    // Extra sessions are created during staged install on temporary basis. They should not be
+    // allowed to live across system server restart.
+    private boolean isExtraSessionForStagedInstall(PackageInstallerSession session) {
+        return (session.params.installFlags & PackageManager.INSTALL_DRY_RUN) != 0
+                || (session.params.installFlags & PackageManager.INSTALL_DISABLE_VERIFICATION) != 0;
+    }
+
     @GuardedBy("mSessions")
     private void addHistoricalSessionLocked(PackageInstallerSession session) {
         CharArrayWriter writer = new CharArrayWriter();