From 1dff1aa97c4ee3ea1436e95fea2fb20c7e8cbead Mon Sep 17 00:00:00 2001
From: Dimitry Ivanov <dimitry@google.com>
Date: Mon, 29 Feb 2016 13:21:43 -0800
Subject: [PATCH] Fix locking of libnativeloader

This commit fixes race condition introduced in
d047c925af62e1fe28fcd1c1940df4afe18d458a

Bug: http://b/27189432
Bug: http://b/22548808
Change-Id: I5d94f130937f18d3443878b3521715a8f87427e0
(cherry picked from commit 34d5a20c8bb57adae8711c7f9d90a77fbd4043c7)
---
 libnativeloader/native_loader.cpp | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/libnativeloader/native_loader.cpp b/libnativeloader/native_loader.cpp
index 9a1f98f86..86d9d77f7 100644
--- a/libnativeloader/native_loader.cpp
+++ b/libnativeloader/native_loader.cpp
@@ -77,8 +77,6 @@ class LibraryNamespaces {
       return nullptr;
     }
 
-    std::lock_guard<std::mutex> guard(mutex_);
-
     android_namespace_t* ns = FindNamespaceByClassLoader(env, class_loader);
 
     LOG_FATAL_IF(ns != nullptr, "There is already a namespace associated with this classloader");
@@ -130,12 +128,12 @@ class LibraryNamespaces {
   }
 
   bool initialized_;
-  std::mutex mutex_;
   std::vector<std::pair<jweak, android_namespace_t*>> namespaces_;
 
   DISALLOW_COPY_AND_ASSIGN(LibraryNamespaces);
 };
 
+static std::mutex g_namespaces_mutex;
 static LibraryNamespaces* g_namespaces = new LibraryNamespaces;
 
 static bool namespaces_enabled(uint32_t target_sdk_version) {
@@ -145,6 +143,7 @@ static bool namespaces_enabled(uint32_t target_sdk_version) {
 
 void PreloadPublicNativeLibraries() {
 #if defined(__ANDROID__)
+  std::lock_guard<std::mutex> guard(g_namespaces_mutex);
   g_namespaces->PreloadPublicLibraries();
 #endif
 }
@@ -161,6 +160,7 @@ jstring CreateClassLoaderNamespace(JNIEnv* env,
     return nullptr;
   }
 
+  std::lock_guard<std::mutex> guard(g_namespaces_mutex);
   android_namespace_t* ns = g_namespaces->Create(env,
                                                  class_loader,
                                                  is_shared,
@@ -186,6 +186,7 @@ void* OpenNativeLibrary(JNIEnv* env,
     return dlopen(path, RTLD_NOW);
   }
 
+  std::lock_guard<std::mutex> guard(g_namespaces_mutex);
   android_namespace_t* ns = g_namespaces->FindNamespaceByClassLoader(env, class_loader);
 
   if (ns == nullptr) {
@@ -210,6 +211,7 @@ void* OpenNativeLibrary(JNIEnv* env,
 
 #if defined(__ANDROID__)
 android_namespace_t* FindNamespaceByClassLoader(JNIEnv* env, jobject class_loader) {
+  std::lock_guard<std::mutex> guard(g_namespaces_mutex);
   return g_namespaces->FindNamespaceByClassLoader(env, class_loader);
 }
 #endif