From cb947bf50bf3e2bd23e0564dfab00e5c2f1e3c9c Mon Sep 17 00:00:00 2001
From: Chris Denton <chris@chrisdenton.dev>
Date: Tue, 3 Nov 2026 21:30:24 +0000
Subject: [PATCH] Disable TLS dtors on process::exit

Running them may be unsound if called within a drop.
---
 library/std/src/sys/exit.rs                        |  2 ++
 .../std/src/sys/thread_local/destructors/list.rs   | 14 ++++++++++++++
 library/std/src/sys/thread_local/mod.rs            |  3 ++-
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/library/std/src/sys/exit.rs b/library/std/src/sys/exit.rs
index 1ca2bd8f6b514..87d48d7fdeb0c 100644
--- a/library/std/src/sys/exit.rs
+++ b/library/std/src/sys/exit.rs
@@ -92,6 +92,8 @@ cfg_select! {
 }
 
 pub fn exit(code: i32) -> ! {
+    // Ensure thread local destructors aren't run on any platform.
+    crate::sys::thread_local::destructors::disable();
     cfg_select! {
         target_os = "hermit" => unsafe { hermit_abi::exit(code) },
         target_os = "linux" => unsafe {
diff --git a/library/std/src/sys/thread_local/destructors/list.rs b/library/std/src/sys/thread_local/destructors/list.rs
index dc767639797fb..2dc075aa1772b 100644
--- a/library/std/src/sys/thread_local/destructors/list.rs
+++ b/library/std/src/sys/thread_local/destructors/list.rs
@@ -1,11 +1,19 @@
 use crate::alloc::System;
 use crate::cell::RefCell;
+use crate::sync::atomic::{Atomic, Ordering};
 use crate::sys::thread_local::guard;
 
 #[thread_local]
 static DTORS: RefCell<Vec<(*mut u8, unsafe extern "C" fn(*mut u8)), System>> =
     RefCell::new(Vec::new_in(System));
 
+static DISABLE_DTORS: Atomic<bool> = Atomic::<bool>::new(false);
+
+/// Permanently disable running TLS dtors.
+pub fn disable() {
+    DISABLE_DTORS.store(true, Ordering::Release);
+}
+
 pub unsafe fn register(t: *mut u8, dtor: unsafe extern "C" fn(*mut u8)) {
     let Ok(mut dtors) = DTORS.try_borrow_mut() else {
         rtabort!("the System allocator may not use TLS with destructors")
@@ -27,6 +35,12 @@ pub unsafe fn register(t: *mut u8, dtor: unsafe extern "C" fn(*mut u8)) {
 /// May only be run on thread exit to guarantee that there are no live references
 /// to TLS variables while they are destroyed.
 pub unsafe fn run() {
+    if DISABLE_DTORS.load(Ordering::Acquire) {
+        if let Ok(mut dtors) = DTORS.try_borrow_mut() {
+            *dtors = Vec::new_in(System);
+        }
+        return;
+    }
     loop {
         let mut dtors = DTORS.borrow_mut();
         match dtors.pop() {
diff --git a/library/std/src/sys/thread_local/mod.rs b/library/std/src/sys/thread_local/mod.rs
index 5d3c23ce04678..add4c83795e20 100644
--- a/library/std/src/sys/thread_local/mod.rs
+++ b/library/std/src/sys/thread_local/mod.rs
@@ -82,12 +82,13 @@ pub(crate) mod destructors {
             mod linux_like;
             mod list;
             pub(super) use linux_like::register;
+            pub(crate) use list::disable;
             pub(super) use list::run;
         }
         _ => {
             mod list;
             pub(super) use list::register;
-            pub(crate) use list::run;
+            pub(crate) use list::{disable, run};
         }
     }
 }