From 9dda4781a43fa2ed43305f57102c0ab3f3795db1 Mon Sep 17 00:00:00 2001
From: arctic-alpaca <67190338+arctic-alpaca@users.noreply.github.com>
Date: Wed, 2 Apr 2025 12:42:05 +0200
Subject: [PATCH] Fix race in POSIX port `vPortEndScheduler`

The `vPortEndScheduler` checks whether it's a FreeRTOS thread after signalling the scheduler thread to stop. This creates a race between the check and the destruction of the thread key. By moving the signal to the scheduler thread after the check, the race is prevented.
---
 portable/ThirdParty/GCC/Posix/port.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/portable/ThirdParty/GCC/Posix/port.c b/portable/ThirdParty/GCC/Posix/port.c
index dd7ca1a9a..1f23ba27a 100644
--- a/portable/ThirdParty/GCC/Posix/port.c
+++ b/portable/ThirdParty/GCC/Posix/port.c
@@ -329,12 +329,17 @@ void vPortEndScheduler( void )
     xTimerTickThreadShouldRun = false;
     pthread_join( hTimerTickThread, NULL );
 
+    /* Check whether the current thread is a FreeRTOS thread.
+     * This has to happen before the scheduler is signaled to exit
+     * its loop to prevent data races on the thread key. */
+    BaseType_t is_freertos_thread = prvIsFreeRTOSThread();
+
     /* Signal the scheduler to exit its loop. */
     xSchedulerEnd = pdTRUE;
     ( void ) pthread_kill( hMainThread, SIG_RESUME );
 
     /* Waiting to be deleted here. */
-    if( prvIsFreeRTOSThread() == pdTRUE )
+    if( is_freertos_thread == pdTRUE )
     {
         pxCurrentThread = prvGetThreadFromTask( xTaskGetCurrentTaskHandle() );
         event_wait( pxCurrentThread->ev );