Adds a fuzzer for LoadEnvironment

node.gyp

@@ -1203,6 +1203,49 @@
         }],
       ],
     }, # fuzz_url
+    { # fuzz_env
+      'target_name': 'fuzz_env',
+      'type': 'executable',
+      'dependencies': [
+        '<(node_lib_target_name)',
+        'deps/histogram/histogram.gyp:histogram',
+        'deps/uvwasi/uvwasi.gyp:uvwasi',
+        'node_dtrace_header',
+        'node_dtrace_ustack',
+        'node_dtrace_provider',
+      ],
+      'includes': [
+        'node.gypi'
+      ],
+      'include_dirs': [
+        'src',
+        'tools/msvs/genfiles',
+        'deps/v8/include',
+        'deps/cares/include',
+        'deps/uv/include',
+        'deps/uvwasi/include',
+        'test/cctest',
+      ],
+      'defines': [
+        'NODE_ARCH="<(target_arch)"',
+        'NODE_PLATFORM="<(OS)"',
+        'NODE_WANT_INTERNALS=1',
+      ],
+      'sources': [
+        'src/node_snapshot_stub.cc',
+        'src/node_code_cache_stub.cc',
+        'test/fuzzers/fuzz_env.cc',
+      ],
+      'conditions': [
+        ['OS=="linux"', {
+          'ldflags': [ '-fsanitize=fuzzer' ]
+        }],
+        # Ensure that ossfuzz flag has been set and that we are on Linux
+        [ 'OS!="linux" or ossfuzz!="true"', {
+          'type': 'none',
+        }],
+      ],
+    }, # fuzz_env
     {
       'target_name': 'cctest',
       'type': 'executable',

test/fuzzers/fuzz_env.cc

@@ -0,0 +1,107 @@
+/*
+ * 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());
+  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;
+}
+

test/fuzzers/fuzz_helper.h

@@ -0,0 +1,42 @@
+struct Argv {
+ public:
+  Argv() : Argv({"node", "-p", "process.version"}) {}
+
+  Argv(const std::initializer_list<const char*> &args) {
+    nr_args_ = args.size();
+    int total_len = 0;
+    for (auto it = args.begin(); it != args.end(); ++it) {
+      total_len += strlen(*it) + 1;
+    }
+    argv_ = static_cast<char**>(malloc(nr_args_ * sizeof(char*)));
+    argv_[0] = static_cast<char*>(malloc(total_len));
+    int i = 0;
+    int offset = 0;
+    for (auto it = args.begin(); it != args.end(); ++it, ++i) {
+      int len = strlen(*it) + 1;
+      snprintf(argv_[0] + offset, len, "%s", *it);
+      // Skip argv_[0] as it points the correct location already
+      if (i > 0) {
+        argv_[i] = argv_[0] + offset;
+      }
+      offset += len;
+    }
+  }
+
+  ~Argv() {
+    free(argv_[0]);
+    free(argv_);
+  }
+
+  int nr_args() const {
+    return nr_args_;
+  }
+
+  char** operator*() const {
+    return argv_;
+  }
+
+ private:
+  char** argv_;
+  int nr_args_;
+};