fix 5.2 audit findings on Windows: F-PROC-1 injection, F-MEM-5 UAF, F-PROC-2 restart race, F-PROC-3, F5, F6

src-tauri/src/lib.rs

@@ -24,6 +24,10 @@ mod shm;
 /// không respawn bridge mới sau khi sidecar đã bị giết (fix: app còn sống
 /// sau khi đóng window → pump thấy stall 3s → spawn bridge mới → orphan).
 static SHUTTING_DOWN: AtomicBool = AtomicBool::new(false);
+// F-PROC-2 (audit 5.2): serialize kill_bridge -> spawn_bridge across the pump
+// watchdog thread and the sample-rate restart command. Without it both threads
+// can kill+spawn concurrently and leave two daw_vst_bridge.exe on the same SHM.
+static BRIDGE_RESTART_LOCK: Mutex<()> = Mutex::new(());
 use shm::{Shm, ShmState};
 
 struct EngineProcess(Mutex<Option<CommandChild>>);
@@ -513,7 +517,22 @@ pub fn run() {
                             );
                             // FIX: kill bridge cũ trước — không được để 2 bridge
                             // cùng map SHM (race control queue / double load).
+                            // F-PROC-2: serialize with the sample-rate restart
+                            // command (same BRIDGE_RESTART_LOCK).
+                            let _restart_guard = match BRIDGE_RESTART_LOCK.lock() {
+                                Ok(g) => g,
+                                Err(p) => p.into_inner(),
+                            };
+                            // F-PROC-3: re-check after acquiring the lock AND
+                            // after kill — Destroyed may have been set while we
+                            // waited/killed; never respawn during app shutdown.
+                            if SHUTTING_DOWN.load(Ordering::Relaxed) {
+                                break;
+                            }
                             kill_bridge(&pump_handle);
+                            if SHUTTING_DOWN.load(Ordering::Relaxed) {
+                                break;
+                            }
                             if spawn_bridge(&pump_handle, &res_dir, &exe_dir, &mut line, &log_path) {
                                 // count restarts into bridge.log (same file as stdout redirect)
                                 let bridge_log = std::path::Path::new(&log_dir)
@@ -672,17 +691,15 @@ fn open_vst_gui(app: AppHandle, plugin_id: String, channel: u8) -> Result<(), St
     // B9: bridge tự tạo native Win32 window cho editor VST3 (không qua
     // WebView2 — HTML window cũ vẽ ĐÈ lên GUI plugin). push_control(4,0,0,0)
     // với hwnd=0 báo bridge tạo window riêng trên ChannelWorker thread.
+    // F5 (audit 5.2): trả Err khi lệnh không tới được bridge (SHM unavailable /
+    // lock poisoned / queue full) — frontend openNativeGUI đã try/catch sẵn.
     let state = app.state::<ShmState>();
-    let lock = state.0.lock();
-    match lock {
-        Ok(guard) => match guard.as_ref() {
-            Some(shm) => {
-                let ok = shm.push_control(4, 0, 0, channel as u32, &plugin_id);
-                eprintln!("open_vst_gui: push_control type=4 hwnd=0 ch={} ok={}", channel, ok);
-            }
-            None => eprintln!("open_vst_gui: bridge shm unavailable"),
-        },
-        Err(e) => eprintln!("open_vst_gui: shm lock poisoned: {}", e),
+    let guard = state.0.lock().map_err(|e| e.to_string())?;
+    let shm = guard.as_ref().ok_or("bridge shm unavailable")?;
+    let ok = shm.push_control(4, 0, 0, channel as u32, &plugin_id);
+    if !ok {
+        eprintln!("open_vst_gui: push_control type=4 hwnd=0 ch={} failed", channel);
+        return Err("control queue full".into());
     }
     Ok(())
 }
@@ -770,6 +787,12 @@ fn restart_bridge_with_sample_rate(app: AppHandle, sample_rate: u32) -> Result<(
             *g = sample_rate;
         }
     }
+    // F-PROC-2: serialize with the pump watchdog restart so two threads can
+    // never both kill+spawn (two bridges on the same SHM).
+    let _restart_guard = match BRIDGE_RESTART_LOCK.lock() {
+        Ok(g) => g,
+        Err(p) => p.into_inner(),
+    };
     kill_bridge(&app);
     let res_dir = app.path().resource_dir().unwrap_or_default();
     let exe_dir = std::env::current_exe()