fuzz_env.cc

/*
 * A fuzzer focused on the node::LoadEnvironment() function.
 *
 * Code here has been inspired by the cctest test case.
 */

#include <stdlib.h>
#include "node.h"
#include "node_platform.h"
#include "node_internals.h"
#include "env-inl.h"
#include "util-inl.h"
#include "v8.h"
#include "libplatform/libplatform.h"
#include "aliased_buffer.h"
#include "fuzz_helper.h"

using node::AliasedBufferBase;

/* General set up */
using ArrayBufferUniquePtr = std::unique_ptr<node::ArrayBufferAllocator,
  decltype(&node::FreeArrayBufferAllocator)>;
using TracingAgentUniquePtr = std::unique_ptr<node::tracing::Agent>;
using NodePlatformUniquePtr = std::unique_ptr<node::NodePlatform>;

static TracingAgentUniquePtr tracing_agent;
static NodePlatformUniquePtr platform;
static uv_loop_t current_loop;

extern "C" int LLVMFuzzerInitialize(int* argc, char*** argv) {
  uv_os_unsetenv("NODE_OPTIONS");
  std::vector<std::string> node_argv{ "fuzz_env" };
  std::vector<std::string> exec_argv;
  std::vector<std::string> errors;

  node::InitializeNodeWithArgs(&node_argv, &exec_argv, &errors);

  tracing_agent = std::make_unique<node::tracing::Agent>();
  node::tracing::TraceEventHelper::SetAgent(tracing_agent.get());
  node::tracing::TracingController* tracing_controller =
    tracing_agent->GetTracingController();  
  CHECK_EQ(0, uv_loop_init(&current_loop));
  static constexpr int kV8ThreadPoolSize = 4;
  platform.reset(
    new node::NodePlatform(kV8ThreadPoolSize, tracing_controller));
  v8::V8::InitializePlatform(platform.get());
  cppgc::InitializeProcess(platform->GetPageAllocator());
  v8::V8::Initialize();
  return 0;
}

class FuzzerFixtureHelper {
public:
  v8::Isolate* isolate_;
  ArrayBufferUniquePtr allocator;

  FuzzerFixtureHelper()
    : allocator(ArrayBufferUniquePtr(node::CreateArrayBufferAllocator(),
                                     &node::FreeArrayBufferAllocator)) {
    isolate_ = NewIsolate(allocator.get(), &current_loop, platform.get());
    CHECK_NOT_NULL(isolate_);
    isolate_->Enter();
  };

  void Teardown() {
    platform->DrainTasks(isolate_);
    isolate_->Exit();
    platform->UnregisterIsolate(isolate_);
    isolate_->Dispose();
    isolate_ = nullptr;
  }
};

void EnvTest(v8::Isolate* isolate_, char* env_string) {
  const v8::HandleScope handle_scope(isolate_);
  Argv argv;

  node::EnvironmentFlags::Flags flags = node::EnvironmentFlags::kDefaultFlags;
  auto isolate = handle_scope.GetIsolate();
  v8::Local<v8::Context> context_ = node::NewContext(isolate);
  context_->Enter();

  node::IsolateData* isolate_data_ = node::CreateIsolateData(isolate, &current_loop,
                                                             platform.get());
  std::vector<std::string> args(*argv, *argv + 1);
  std::vector<std::string> exec_args(*argv, *argv + 1);
  node::Environment* environment_ = node::CreateEnvironment(isolate_data_,
                                          context_, args, exec_args, flags);
  node::Environment* envi = environment_;
  SetProcessExitHandler(envi, [&](node::Environment* env_, int exit_code) {
    node::Stop(envi);
  });
  node::LoadEnvironment(envi, env_string);

  // Cleanup!
  node::FreeEnvironment(environment_);
  node::FreeIsolateData(isolate_data_);
  context_->Exit();
}

extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data2, size_t size) {
  FuzzerFixtureHelper ffh;
  std::string s(reinterpret_cast<const char*>(data2), size);
  EnvTest(ffh.isolate_, (char*)s.c_str());
  ffh.Teardown();
  return 0;
}