From 958ff67cccfec6ebac93f5ba90c07d804d916840 Mon Sep 17 00:00:00 2001
From: Simon Frei <freisim93@gmail.com>
Date: Mon, 20 Nov 2023 08:12:25 +0100
Subject: [PATCH] lib/model: Acquire fmut lock in ensureIndexHandler (fixes
 #9234) (#9235)

Towards the end of the function f.folderCfgs and f.folderRunners are
read without the lock.
---
 lib/model/model.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/model/model.go b/lib/model/model.go
index c8007f61d..64475468d 100644
--- a/lib/model/model.go
+++ b/lib/model/model.go
@@ -1346,6 +1346,9 @@ func (m *model) ensureIndexHandler(conn protocol.Connection) *indexHandlerRegist
 	deviceID := conn.DeviceID()
 	connID := conn.ConnectionID()
 
+	// We must acquire fmut first when acquiring both locks.
+	m.fmut.RLock()
+	defer m.fmut.RUnlock()
 	m.pmut.Lock()
 	defer m.pmut.Unlock()