From f30f0c1938935338605bb0edb77c3c2e90f60822 Mon Sep 17 00:00:00 2001
From: Willy-JL <49810075+Willy-JL@users.noreply.github.com>
Date: Sat, 9 Nov 2024 04:42:34 +0000
Subject: [PATCH] Furi: Fix Semaphore atomicity

if thread A waiting for acquire(), thread B calls release()
halfway through release() code, A would
wake up and continue, before B finishes release()
this could cause use-after-free if A free()s semaphore after acquire
---
 furi/core/semaphore.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/furi/core/semaphore.c b/furi/core/semaphore.c
index d05b9bf09..513c3a122 100644
--- a/furi/core/semaphore.c
+++ b/furi/core/semaphore.c
@@ -104,6 +104,8 @@ FuriStatus furi_semaphore_release(FuriSemaphore* instance) {
 
     stat = FuriStatusOk;
 
+    FURI_CRITICAL_ENTER();
+
     if(FURI_IS_IRQ_MODE()) {
         yield = pdFALSE;
 
@@ -123,6 +125,8 @@ FuriStatus furi_semaphore_release(FuriSemaphore* instance) {
         furi_event_loop_link_notify(&instance->event_loop_link, FuriEventLoopEventIn);
     }
 
+    FURI_CRITICAL_EXIT();
+
     return stat;
 }