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src/node_errors: add re-entrancy guard to TriggerUncaughtException #64327

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src/node_errors: add re-entrancy guard to TriggerUncaughtException #64327

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src/node_errors: add re-entrancy guard to prevent infinite recursion …
themuuln Jul 6, 2026
b9c03ae
src/node_errors: document re-entrancy guard
themuuln Jul 7, 2026
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23 changes: 23 additions & 0 deletions src/node_errors.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -191,6 +191,9 @@ static std::string GetErrorSource(Isolate* isolate,

static std::atomic<bool> is_in_oom{false};
static thread_local std::atomic<bool> is_retrieving_js_stacktrace{false};
// This is thread-local because it only guards re-entrancy within the current
// thread's uncaught-exception path; no cross-thread synchronization is needed.
static thread_local bool is_in_uncaught_exception = false;

@jasnell jasnell Jul 7, 2026

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Does this need to be std::atomic<bool> like is_retrieving_js_stacktrace? If not, a short comment explaining why would be good.

@themuuln themuuln Jul 7, 2026

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Fair enough — added a comment explaining why. Since this flag only guards re-entrancy on the current thread, thread_local handles the isolation and no atomic is needed.

MaybeLocal<StackTrace> GetCurrentStackTrace(Isolate* isolate, int frame_count) {
if (isolate == nullptr) {
return MaybeLocal<StackTrace>();
Expand Down Expand Up @@ -1278,6 +1281,26 @@ void TriggerUncaughtException(Isolate* isolate,
CHECK(isolate->InContext());
Local<Context> context = isolate->GetCurrentContext();
Environment* env = Environment::GetCurrent(context);
// Re-entrancy guard: prevent infinite recursion when the JS-level
// exception handler (process._fatalException) itself triggers another
// exception through the inspector protocol, causing V8's pending message
// reporting to call TriggerUncaughtException reentrantly.
if (is_in_uncaught_exception) {
PrintToStderrAndFlush(
"FATAL ERROR: Re-entrant uncaught exception detected.\n"
"The exception handler threw an error while processing a\n"
"previous uncaught exception, likely due to an inspector\n"
"protocol issue. Aborting to prevent infinite recursion.\n" +
FormatCaughtException(isolate, context, error, message));
ABORT();
}
// RAII guard to ensure the flag is cleared when TriggerUncaughtException
// returns normally. Note: ABORT() and env->Exit() do not run this
// destructor, which is intentional — the process is terminating.
struct UncaughtExceptionGuard {
UncaughtExceptionGuard() { is_in_uncaught_exception = true; }
~UncaughtExceptionGuard() { is_in_uncaught_exception = false; }
} uncaught_exception_guard;
if (env == nullptr) {
// This means that the exception happens before Environment is assigned
// to the context e.g. when there is a SyntaxError in a per-context
Expand Down