From 887b92bfe2b937c70c32b7bddde6e52bb760ae71 Mon Sep 17 00:00:00 2001
From: Neil Twigg <neil@nats.io>
Date: Tue, 19 Sep 2023 16:50:48 +0100
Subject: [PATCH] Fix data race in `setStreamAssignment` by ensuring JS lock
 held

Signed-off-by: Neil Twigg <neil@nats.io>
---
 server/stream.go | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/server/stream.go b/server/stream.go
index d66f6062..196c1def 100644
--- a/server/stream.go
+++ b/server/stream.go
@@ -747,6 +747,7 @@ func (mset *stream) streamAssignment() *streamAssignment {
 
 func (mset *stream) setStreamAssignment(sa *streamAssignment) {
 	var node RaftNode
+	var peers []string
 
 	mset.mu.RLock()
 	js := mset.js
@@ -756,6 +757,7 @@ func (mset *stream) setStreamAssignment(sa *streamAssignment) {
 		js.mu.RLock()
 		if sa.Group != nil {
 			node = sa.Group.node
+			peers = sa.Group.Peers
 		}
 		js.mu.RUnlock()
 	}
@@ -771,7 +773,7 @@ func (mset *stream) setStreamAssignment(sa *streamAssignment) {
 	// Set our node.
 	mset.node = node
 	if mset.node != nil {
-		mset.node.UpdateKnownPeers(sa.Group.Peers)
+		mset.node.UpdateKnownPeers(peers)
 	}
 
 	// Setup our info sub here as well for all stream members. This is now by design.