From b665e9e6a2752aba2dcb9a73b00c086a5122f595 Mon Sep 17 00:00:00 2001
From: Ben Dean-Kawamura <bdk@mozilla.com>
Date: Fri, 26 Sep 2025 11:58:26 -0400
Subject: [PATCH] Avoid threading issues in sortFields (#1686)

Copy the fields array from `getFieldList`, this avoids the possibility
of 2 threads trying to mutate it at once in the call `sortFields` at the
bottom of the function.
---
 CHANGES.md                     | 2 +-
 src/com/sun/jna/Structure.java | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index 9b149a2da..12193a152 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -10,7 +10,7 @@ Features
 
 Bug Fixes
 ---------
-
+* [#1686](https://github.com/java-native-access/jna/issues/1686): Fix `sortFields` race condition while getting fields
 
 Release 5.18.0
 ==============
diff --git a/src/com/sun/jna/Structure.java b/src/com/sun/jna/Structure.java
index 12e03f7fa..6a7d0c4df 100644
--- a/src/com/sun/jna/Structure.java
+++ b/src/com/sun/jna/Structure.java
@@ -1125,7 +1125,7 @@ private static <T extends Comparable<T>> List<T> sort(Collection<? extends T> c)
         and can't be generated automatically.
     **/
     protected List<Field> getFields(boolean force) {
-        List<Field> flist = getFieldList();
+        List<Field> flist = new ArrayList<>(getFieldList());
         Set<String> names = new HashSet<>();
         for (Field f : flist) {
             names.add(f.getName());