trace_events: forbid tracing modifications from worker threads

Forbid modifying tracing state from worker threads, either
through the built-in module or inspector sessions, since
the main thread owns all global state, and at least
the `async_hooks` integration is definitely not thread
safe in its current state.

PR-URL: https://github.com/nodejs/node/pull/23781
Fixes: https://github.com/nodejs/node/issues/22767
Refs: https://github.com/nodejs/node/issues/22513
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Matheus Marchini <mat@mmarchini.me>

1 files changed, 12 insertions, 1 deletions

diff --git a/src/env.cc b/src/env.cc
index 5da673b3e0..383df37aab 100644
--- a/src/env.cc
+++ b/src/env.cc
@@ -128,11 +128,22 @@ void InitThreadLocalOnce() {
 }
 
 void Environment::TrackingTraceStateObserver::UpdateTraceCategoryState() {
+  if (!env_->is_main_thread()) {
+    // Ideally, we’d have a consistent story that treats all threads/Environment
+    // instances equally here. However, tracing is essentially global, and this
+    // callback is called from whichever thread calls `StartTracing()` or
+    // `StopTracing()`. The only way to do this in a threadsafe fashion
+    // seems to be only tracking this from the main thread, and only allowing
+    // these state modifications from the main thread.
+    return;
+  }
+
   env_->trace_category_state()[0] =
       *TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED(
           TRACING_CATEGORY_NODE1(async_hooks));
 
   Isolate* isolate = env_->isolate();
+  HandleScope handle_scope(isolate);
   Local<Function> cb = env_->trace_category_state_function();
   if (cb.IsEmpty())
     return;
@@ -182,7 +193,7 @@ Environment::Environment(IsolateData* isolate_data,
   AssignToContext(context, ContextInfo(""));
 
   if (tracing::AgentWriterHandle* writer = GetTracingAgentWriter()) {
-    trace_state_observer_.reset(new TrackingTraceStateObserver(this));
+    trace_state_observer_ = std::make_unique<TrackingTraceStateObserver>(this);
     v8::TracingController* tracing_controller = writer->GetTracingController();
     if (tracing_controller != nullptr)
       tracing_controller->AddTraceStateObserver(trace_state_observer_.get());