From da3a9486a868949604557ffd0d7adf2d654d5b3f Mon Sep 17 00:00:00 2001
From: James M Snell <jasnell@gmail.com>
Date: Sun, 24 Jan 2021 10:00:57 -0800
Subject: [PATCH] buffer: avoid creating the backing store in the thread

Fixes: https://github.com/nodejs/node/issues/37030

PR-URL: https://github.com/nodejs/node/pull/37052
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
---
 src/node_blob.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/node_blob.cc b/src/node_blob.cc
index b147b8764a7668..0b18bbce138e35 100644
--- a/src/node_blob.cc
+++ b/src/node_blob.cc
@@ -254,8 +254,6 @@ void FixedSizeBlobCopyJob::AfterThreadPoolWork(int status) {
 }
 
 void FixedSizeBlobCopyJob::DoThreadPoolWork() {
-  Environment* env = AsyncWrap::env();
-  destination_ = ArrayBuffer::NewBackingStore(env->isolate(), length_);
   unsigned char* dest = static_cast<unsigned char*>(destination_->Data());
   if (length_ > 0) {
     size_t total = 0;
@@ -314,6 +312,8 @@ void FixedSizeBlobCopyJob::Run(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
   FixedSizeBlobCopyJob* job;
   ASSIGN_OR_RETURN_UNWRAP(&job, args.Holder());
+  job->destination_ =
+      ArrayBuffer::NewBackingStore(env->isolate(), job->length_);
   if (job->mode() == FixedSizeBlobCopyJob::Mode::ASYNC)
     return job->ScheduleWork();