From b4ec5b8f1d728d73d0e5449360a3352f5887b707 Mon Sep 17 00:00:00 2001
From: Matt Broadstone <mbroadst@mongodb.com>
Date: Sat, 21 Dec 2019 08:28:34 -0500
Subject: [PATCH] fix(gridfs): make a copy of chunk before writing to server

A shared buffer is used for gridfs uploads, but there is a race
where the buffer could be changed before the write has a chance to
execute. Instead, we cut a copy of the buffer for use during the
write operation.
---
 lib/gridfs-stream/upload.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/gridfs-stream/upload.js b/lib/gridfs-stream/upload.js
index 40e1eab3ff..578949a53d 100644
--- a/lib/gridfs-stream/upload.js
+++ b/lib/gridfs-stream/upload.js
@@ -422,7 +422,7 @@ function doWrite(_this, chunk, encoding, callback) {
       if (_this.md5) {
         _this.md5.update(_this.bufToStore);
       }
-      var doc = createChunkDoc(_this.id, _this.n, _this.bufToStore);
+      var doc = createChunkDoc(_this.id, _this.n, Buffer.from(_this.bufToStore));
       ++_this.state.outstandingRequests;
       ++outstandingRequests;