From fab68e1481d8260e0b8c3e465ea8e2b5032a0cfe Mon Sep 17 00:00:00 2001
From: Hans Boehm <hboehm@google.com>
Date: Tue, 23 Mar 2021 11:31:43 -0700
Subject: [PATCH] Don't fork USAPs with open argument buffer

Delay execution of any zygote command that may end up forking USAPs
until we've released our own ZygoteCommandBuffer. Otherwise we fork
the child with an open ZygoteCommandBuffer, preventing it from
opening its own.

Bug: 182084594
Test: Build and boot AOSP, with USAPs enabled and disabled.
Change-Id: I2366367d2155a120092fbdcae13cbb3d7f4e1d16
---
 .../android/internal/os/ZygoteConnection.java | 31 ++++++++++---------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/core/java/com/android/internal/os/ZygoteConnection.java b/core/java/com/android/internal/os/ZygoteConnection.java
index 1673362028f9e..993e4e7b4b3d0 100644
--- a/core/java/com/android/internal/os/ZygoteConnection.java
+++ b/core/java/com/android/internal/os/ZygoteConnection.java
@@ -149,8 +149,11 @@ class ZygoteConnection {
                     return null;
                 }
 
-                if (parsedArgs.mUsapPoolStatusSpecified) {
-                    // Handle this once we've released the argBuffer, to avoid opening a second one.
+                if (parsedArgs.mUsapPoolStatusSpecified
+                        || parsedArgs.mApiDenylistExemptions != null
+                        || parsedArgs.mHiddenApiAccessLogSampleRate != -1
+                        || parsedArgs.mHiddenApiAccessStatslogSampleRate != -1) {
+                    // Handle these once we've released argBuffer, to avoid opening a second one.
                     break;
                 }
 
@@ -183,18 +186,6 @@ class ZygoteConnection {
                     return null;
                 }
 
-                if (parsedArgs.mApiDenylistExemptions != null) {
-                    return handleApiDenylistExemptions(zygoteServer,
-                            parsedArgs.mApiDenylistExemptions);
-                }
-
-                if (parsedArgs.mHiddenApiAccessLogSampleRate != -1
-                        || parsedArgs.mHiddenApiAccessStatslogSampleRate != -1) {
-                    return handleHiddenApiAccessLogSampleRate(zygoteServer,
-                            parsedArgs.mHiddenApiAccessLogSampleRate,
-                            parsedArgs.mHiddenApiAccessStatslogSampleRate);
-                }
-
                 if (parsedArgs.mPermittedCapabilities != 0
                         || parsedArgs.mEffectiveCapabilities != 0) {
                     throw new ZygoteSecurityException("Client may not specify capabilities: "
@@ -311,10 +302,20 @@ class ZygoteConnection {
                 }
             }
         }
+        // Handle anything that may need a ZygoteCommandBuffer after we've released ours.
         if (parsedArgs.mUsapPoolStatusSpecified) {
-            // Now that we've released argBuffer:
             return handleUsapPoolStatusChange(zygoteServer, parsedArgs.mUsapPoolEnabled);
         }
+        if (parsedArgs.mApiDenylistExemptions != null) {
+            return handleApiDenylistExemptions(zygoteServer,
+                    parsedArgs.mApiDenylistExemptions);
+        }
+        if (parsedArgs.mHiddenApiAccessLogSampleRate != -1
+                || parsedArgs.mHiddenApiAccessStatslogSampleRate != -1) {
+            return handleHiddenApiAccessLogSampleRate(zygoteServer,
+                    parsedArgs.mHiddenApiAccessLogSampleRate,
+                    parsedArgs.mHiddenApiAccessStatslogSampleRate);
+        }
         throw new AssertionError("Shouldn't get here");
     }