Prevent crashes during exit due to deregistering frames on exit (v2)

lib/compiler/src/engine/unwind/systemv.rs

@@ -3,7 +3,11 @@
 
 //! Module for System V ABI unwind registry.
 
-use core::sync::atomic::{AtomicUsize, Ordering::Relaxed};
+use core::sync::atomic::{
+    AtomicBool, AtomicUsize,
+    Ordering::{self, Relaxed},
+};
+use std::sync::Once;
 
 use crate::types::unwind::CompiledFunctionUnwindInfoReference;
 
@@ -139,6 +143,12 @@ impl UnwindRegistry {
 
     #[allow(clippy::cast_ptr_alignment)]
     unsafe fn register_frames(&mut self, eh_frame: &[u8]) {
+        // Register atexit handler that will tell us if exit has been called.
+        static INIT: Once = Once::new();
+        INIT.call_once(|| unsafe {
+            libc::atexit(atexit_handler);
+        });
+
         #[cfg(all(target_os = "macos", target_arch = "aarch64"))]
         {
             // Special call for macOS on aarch64 to register the `.eh_frame` section.
@@ -151,6 +161,9 @@ impl UnwindRegistry {
 
         #[cfg(not(all(target_os = "macos", target_arch = "aarch64")))]
         {
+            // Leak the `.eh_frame` to ensure it lives long enough
+            let eh_frame: &mut [u8] = Box::leak(Box::from(eh_frame));
+
             // Validate that the `.eh_frame` is well-formed before registering it.
             // See https://refspecs.linuxfoundation.org/LSB_3.0.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html for more details.
             // We put the frame records into a vector before registering them, because
@@ -237,6 +250,12 @@ impl UnwindRegistry {
     }
 }
 
+static EXIT_CALLED: AtomicBool = AtomicBool::new(false);
+
+extern "C" fn atexit_handler() {
+    EXIT_CALLED.store(true, Ordering::SeqCst);
+}
+
 impl Drop for UnwindRegistry {
     fn drop(&mut self) {
         if self.published {
@@ -258,6 +277,12 @@ impl Drop for UnwindRegistry {
 
                     #[cfg(not(all(target_os = "macos", target_arch = "aarch64")))]
                     {
+                        // We don't want to deregister frames in UnwindRegistry::Drop as that could be called during
+                        // program shutdown and can collide with release_registered_frames and lead to
+                        // crashes.
+                        if EXIT_CALLED.load(Ordering::SeqCst) {
+                            return;
+                        }
                         __deregister_frame(*registration as *const _);
                     }
                 }