Skip to content

Fix use-after-free in XMLHttpRequest::Send continuation #190

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
bkaradzic-microsoft merged 1 commit into from
Jun 9, 2026
Merged

Fix use-after-free in XMLHttpRequest::Send continuation #190

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
14 changes: 13 additions & 1 deletion Polyfills/XMLHttpRequest/Source/XMLHttpRequest.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -259,11 +259,23 @@ namespace Babylon::Polyfills::Internal

std::string traceName = (std::ostringstream{} << "XMLHttpRequest::Send [" << m_url << "]").str();
auto sendRegion = std::make_optional<arcana::trace_region>(traceName.c_str());

// Keep the JS wrapper (and therefore this C++ object) alive for the
// duration of the asynchronous request. The continuation below captures
// `this` raw and dereferences members when the request settles; without
// an anchor, GC may collect the wrapper while the request is in flight
// (e.g. once the requesting script drops its reference) and the
// continuation would then run on a freed `this`. The anchor lives in a
// shared_ptr owned by the continuation lambda, so it is released
// automatically once the request settles and the lambda is destroyed --
// no member self-reference to clear. (Mirrors FileReader's anchor.)
auto anchor = std::make_shared<Napi::ObjectReference>(Napi::Persistent(info.This().As<Napi::Object>()));

m_request.SendAsync()
.then(arcana::inline_scheduler, arcana::cancellation::none(), [sendRegion{std::move(sendRegion)}]() mutable {
sendRegion.reset();
})
.then(m_runtimeScheduler, arcana::cancellation::none(), [this](const arcana::expected<void, std::exception_ptr>& result) {
.then(m_runtimeScheduler, arcana::cancellation::none(), [this, anchor{std::move(anchor)}](const arcana::expected<void, std::exception_ptr>& result) {
// Run on every outcome -- transport exception OR underlying request succeeded but ended in a non-2xx
// status (e.g. a missing local file on UWP, where UrlLib silently retains status 0). The previous
// success-only continuation here skipped readyState=Done / loadend / error and let the JS observer
Expand Down
Loading