From 678aa48a12b1a1fa11414c192c46eec782be3082 Mon Sep 17 00:00:00 2001
From: Jacquin Antoine <antoine@arkel.fr>
Date: Sun, 19 Apr 2026 14:34:30 +0200
Subject: [PATCH] fix(correlation): prevent race condition in session manager

Fixed potential use-after-free in Update() when gcRound deletes
a session between GetOrCreate() and acquiring the session lock.

Changes:
- Add 'deleted' flag to SessionState
- Mark sessions as deleted before removing from map in gcRound
- Check deleted flag in Update and recreate session if needed

This ensures updates to deleted sessions create a new session
instead of modifying a freed/dangling reference.

Race detector verified: go test ./internal/correlation/... -race

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 .../ja4ebpf/internal/correlation/manager.go     | 17 +++++++++++++++++
 .../ja4ebpf/internal/correlation/session.go     |  3 ++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/services/ja4ebpf/internal/correlation/manager.go b/services/ja4ebpf/internal/correlation/manager.go
index 1fa195a..50187cb 100644
--- a/services/ja4ebpf/internal/correlation/manager.go
+++ b/services/ja4ebpf/internal/correlation/manager.go
@@ -84,10 +84,21 @@ func (m *Manager) GetOrCreate(key SessionKey) *SessionState {
 
 // Update applique la fonction fn sur la session identifiée par key,
 // en créant la session si elle n'existe pas encore.
+// Thread-safe : vérifie le flag deleted pour éviter les use-after-free.
 func (m *Manager) Update(key SessionKey, fn func(*SessionState)) {
 	s := m.GetOrCreate(key)
+
 	s.mu.Lock()
 	defer s.mu.Unlock()
+
+	// Vérifier si la session a été marquée comme supprimée par gcRound
+	if s.deleted {
+		// La session a été supprimée, recréer une nouvelle session
+		s = m.GetOrCreate(key)
+		s.mu.Lock()
+		defer s.mu.Unlock()
+	}
+
 	fn(s)
 	s.LastActivity = time.Now()
 }
@@ -128,6 +139,12 @@ func (m *Manager) gcRound(slowlorisThreshold time.Duration) {
 
 			if expired || slowloris {
 				toDelete = append(toDelete, key)
+				// Marquer la session comme supprimée AVANT de l'envoyer à ReadyCh
+				// pour éviter les race conditions avec Update()
+				s.mu.Lock()
+				s.deleted = true
+				s.mu.Unlock()
+
 				// Envoyer sans bloquer (drop si le canal est plein)
 				select {
 				case m.ReadyCh <- s:
diff --git a/services/ja4ebpf/internal/correlation/session.go b/services/ja4ebpf/internal/correlation/session.go
index b23d429..fa21568 100644
--- a/services/ja4ebpf/internal/correlation/session.go
+++ b/services/ja4ebpf/internal/correlation/session.go
@@ -88,7 +88,8 @@ type SessionState struct {
 	FirstSeen    time.Time // horodatage de création de la session
 	LastActivity time.Time // horodatage de la dernière activité
 
-	mu sync.Mutex // protection des modifications concurrentes
+	deleted bool // true si la session a été supprimée du map par gcRound
+	mu      sync.Mutex // protection des modifications concurrentes
 }
 
 // IsExpired indique si la session n'a reçu aucune activité depuis timeout.