fix(mqtt): FR-011 Heap-Korruption bei TLS-Verbindungsabbruch

- _rebuildClient(): WiFiClientSecure + PubSubClient vor jedem Reconnect-Versuch sauber delete + new auf Core 0 - mbedTLS startet damit immer mit sauberem Heap-Kontext - Verhindert CORRUPT HEAP / PANIC wenn Broker die TLS-Session unerwartet abbricht (MBEDTLS_ERR_NET_CONN_RESET) - _broker/_port als Members gecacht fuer _rebuildClient()
2026-03-01 17:50:18 +01:00 · 2026-03-01 17:50:18 +01:00 · 1ef0464be9
commit 1ef0464be9
parent c61a67f812
5 changed files with 111 additions and 33 deletions
--- a/Feature-Requests.md
+++ b/Feature-Requests.md
@ -19,6 +19,23 @@ Status: `[ ]` = offen · `[x]` = erledigt

 ## Offen

+- [ ] **FR-011** Bug: PANIC/EXCEPTION durch Heap-Korruption bei MQTT-Verbindungsabbruch (TLS)
+  - **Symptom**: ESP32 crasht mit `CORRUPT HEAP: Bad tail` + `assert failed: multi_heap_free` wenn der MQTT-Broker nicht erreichbar ist und eine bestehende TLS-Session unerwartet abbricht
+  - **Fehlermeldung**: `(-76) UNKNOWN ERROR CODE (004C)` = `MBEDTLS_ERR_NET_CONN_RESET`
+  - **Crash-Kette**:
+    1. Broker bricht TLS-Verbindung ab (Connection reset by peer)
+    2. `PubSubClient::connected()` → `WiFiClientSecure::connected()` → `available()`
+    3. `available()` erkennt EOF → ruft intern `stop()` → `stop_ssl_socket()` auf
+    4. `mbedtls_ssl_free()` wird auf einem bereits inkonsistenten SSL-Kontext aufgerufen
+    5. Heap-Corruption → `multi_heap_free` assert → PANIC
+  - **Backtrace-Frames**: `multi_heap_free` ← `heap_caps_free` ← `esp_mbedtls_mem_free` ← `mbedtls_free` ← `mbedtls_ssl_free` ← `stop_ssl_socket` ← `WiFiClientSecure::stop()` ← `WiFiClientSecure::available()` ← `WiFiClientSecure::connected()` ← `PubSubClient::connected()` ← `MqttClient::_taskLoop()`
+  - **Root Cause**: `WiFiClientSecure`-Objekt (`_espClient`) wird nach einem TLS-Verbindungsabbruch nicht neu erstellt — der interne mbedTLS-State ist korrupt, beim nächsten `connected()`-Aufruf crasht `mbedtls_ssl_free()`
+  - **Fix-Strategie**: Nach jedem fehlgeschlagenen Verbindungsversuch (`rc == -2` oder `!client->connected()`) das `WiFiClientSecure`-Objekt zerstören und neu auf Core 0 erstellen (`delete _espClient; _espClient = new WiFiClientSecure(); _espClient->setInsecure(); _client->setClient(*_espClient)`). Damit startet mbedTLS immer mit einem sauberen Kontext.
+  - **Reproduktion**: Broker stoppen während aktiver TLS-Session → innerhalb weniger Minuten PANIC
+  - Betroffene Dateien: `src/mqtt_client.cpp`, `include/mqtt_client.h`
+  - Commit: `TODO`
+  - Version: 1.4.1
+
 ---

 ## Erledigt
@ -46,7 +63,7 @@ Status: `[ ]` = offen · `[x]` = erledigt
  - **Heartbeat `lasercutter/status`**: Feld `"display_on": true/false` hinzugefügt
  - **`DisplayManager`**: `setEnabled()` / `isEnabled()` via MAX7219 SHUTDOWN-Modus
  - Betroffene Dateien: `src/web_server.cpp`, `src/mqtt_client.cpp`, `include/config.h`, `include/display_manager.h`, `src/display_manager.cpp`
-  - Commit: `TODO`
+  - Commit: `c61a67f`
  - Version: 1.4.0

 ### Version 1.2.0
--- a/doc/Front.svg
+++ b/doc/Front.svg
@ -24,8 +24,8 @@
     inkscape:deskcolor="#d1d1d1"
     inkscape:document-units="mm"
     inkscape:zoom="0.71891835"
-     inkscape:cx="584.90648"
-     inkscape:cy="639.15464"
+     inkscape:cx="634.98171"
+     inkscape:cy="835.28262"
     inkscape:window-width="1920"
     inkscape:window-height="1009"
     inkscape:window-x="1912"
@ -149,56 +149,62 @@
       xml:space="preserve"
       style="font-weight:600;font-size:7.40833px;line-height:0;font-family:'Open Sans';-inkscape-font-specification:'Open Sans, Semi-Bold';text-align:end;writing-mode:lr-tb;direction:ltr;text-anchor:end;fill:#000000;stroke:#241212;stroke-width:0.2;stroke-linejoin:bevel;stroke-opacity:1"
       x="204.76865"
-       y="256.40359"
+       y="262.22452"
       id="text4"><tspan
         sodipodi:role="line"
         id="tspan4"
         style="fill:#000000;stroke-width:0.2"
         x="204.76865"
-         y="256.40359">Freie Testzeit</tspan><tspan
+         y="262.22452">Freie Testzeit</tspan><tspan
         sodipodi:role="line"
         style="fill:#000000;stroke-width:0.2"
         x="204.76865"
-         y="256.40359"
+         y="262.22452"
         id="tspan5" /></text>
    <text
       xml:space="preserve"
       style="font-weight:600;font-size:7.40833px;line-height:0;font-family:'Open Sans';-inkscape-font-specification:'Open Sans, Semi-Bold';text-align:end;writing-mode:lr-tb;direction:ltr;text-anchor:end;fill:#000000;stroke:#241212;stroke-width:0.2;stroke-linejoin:bevel;stroke-opacity:1"
       x="203.7793"
-       y="265.51187"
+       y="271.33279"
       id="text6"><tspan
         sodipodi:role="line"
         id="tspan6"
         style="fill:#000000;stroke-width:0.2"
         x="203.7793"
-         y="265.51187">in Sekunden</tspan></text>
+         y="271.33279">in Sekunden</tspan></text>
    <text
       xml:space="preserve"
-       style="font-style:normal;font-variant:normal;font-weight:600;font-stretch:normal;font-size:5.29167px;line-height:0;font-family:'Open Sans';-inkscape-font-specification:'Open Sans, Semi-Bold';font-variant-ligatures:normal;font-variant-caps:normal;font-variant-numeric:normal;font-variant-east-asian:normal;text-align:end;writing-mode:lr-tb;direction:ltr;text-anchor:end;fill:#000000;stroke:#241212;stroke-width:0.2;stroke-linejoin:bevel;stroke-opacity:1"
-       x="144.94814"
-       y="256.01343"
+       style="font-style:normal;font-variant:normal;font-weight:600;font-stretch:normal;font-size:5.29167px;line-height:0;font-family:'Open Sans';-inkscape-font-specification:'Open Sans, Semi-Bold';font-variant-ligatures:normal;font-variant-caps:normal;font-variant-numeric:normal;font-variant-east-asian:normal;text-align:end;writing-mode:lr-tb;direction:ltr;text-anchor:end;fill:#000000;stroke:#422020;stroke-width:0.2;stroke-linejoin:bevel;stroke-opacity:1"
+       x="226.37459"
+       y="252.96211"
       id="text4-0"><tspan
         id="tspan4-6"
-         style="font-style:normal;font-variant:normal;font-weight:600;font-stretch:normal;font-size:5.29167px;font-family:'Open Sans';-inkscape-font-specification:'Open Sans, Semi-Bold';font-variant-ligatures:normal;font-variant-caps:normal;font-variant-numeric:normal;font-variant-east-asian:normal;fill:#000000;stroke-width:0.2"
-         x="144.94814"
-         y="256.01343"
-         sodipodi:role="line">€ Laserzeit</tspan><tspan
-         style="font-style:normal;font-variant:normal;font-weight:600;font-stretch:normal;font-size:5.29167px;font-family:'Open Sans';-inkscape-font-specification:'Open Sans, Semi-Bold';font-variant-ligatures:normal;font-variant-caps:normal;font-variant-numeric:normal;font-variant-east-asian:normal;fill:#000000;stroke-width:0.2"
-         x="144.94814"
-         y="256.01343"
+         style="font-style:normal;font-variant:normal;font-weight:600;font-stretch:normal;font-size:5.29167px;font-family:'Open Sans';-inkscape-font-specification:'Open Sans, Semi-Bold';font-variant-ligatures:normal;font-variant-caps:normal;font-variant-numeric:normal;font-variant-east-asian:normal;fill:#000000;stroke-width:0.2;stroke:#422020;stroke-opacity:1"
+         x="226.37459"
+         y="252.96211"
+         sodipodi:role="line">€ Laserzeit in Sekunden </tspan><tspan
+         style="font-style:normal;font-variant:normal;font-weight:600;font-stretch:normal;font-size:5.29167px;font-family:'Open Sans';-inkscape-font-specification:'Open Sans, Semi-Bold';font-variant-ligatures:normal;font-variant-caps:normal;font-variant-numeric:normal;font-variant-east-asian:normal;fill:#000000;stroke-width:0.2;stroke:#422020;stroke-opacity:1"
+         x="226.37459"
+         y="252.96211"
         id="tspan5-1"
         sodipodi:role="line" /></text>
    <text
       xml:space="preserve"
       style="font-style:normal;font-variant:normal;font-weight:600;font-stretch:normal;font-size:5.29167px;line-height:0;font-family:'Open Sans';-inkscape-font-specification:'Open Sans, Semi-Bold';font-variant-ligatures:normal;font-variant-caps:normal;font-variant-numeric:normal;font-variant-east-asian:normal;text-align:end;writing-mode:lr-tb;direction:ltr;text-anchor:end;fill:#000000;stroke:#241212;stroke-width:0.2;stroke-linejoin:bevel;stroke-opacity:1"
-       x="144.02959"
-       y="265.11499"
-       id="text6-3"><tspan
-         sodipodi:role="line"
-         id="tspan6-8"
+       x="-218.73421"
+       y="225.72589"
+       id="text4-0-7"
+       transform="rotate(-89.846243)"><tspan
+         id="tspan4-6-6"
         style="font-style:normal;font-variant:normal;font-weight:600;font-stretch:normal;font-size:5.29167px;font-family:'Open Sans';-inkscape-font-specification:'Open Sans, Semi-Bold';font-variant-ligatures:normal;font-variant-caps:normal;font-variant-numeric:normal;font-variant-east-asian:normal;fill:#000000;stroke-width:0.2"
-         x="144.02959"
-         y="265.11499">Sekunden</tspan></text>
+         x="-218.73421"
+         y="225.72589"
+         sodipodi:role="line">umlaufend</tspan><tspan
+         style="font-style:normal;font-variant:normal;font-weight:600;font-stretch:normal;font-size:5.29167px;font-family:'Open Sans';-inkscape-font-specification:'Open Sans, Semi-Bold';font-variant-ligatures:normal;font-variant-caps:normal;font-variant-numeric:normal;font-variant-east-asian:normal;fill:#000000;stroke-width:0.2"
+         x="-218.73421"
+         y="225.72589"
+         id="tspan5-1-1"
+         sodipodi:role="line" /></text>
    <text
       xml:space="preserve"
       style="font-weight:600;font-size:7.40833px;line-height:0;font-family:'Open Sans';-inkscape-font-specification:'Open Sans, Semi-Bold';text-align:end;writing-mode:lr-tb;direction:ltr;text-anchor:end;fill:#000000;stroke:#241212;stroke-width:0.2;stroke-linejoin:bevel;stroke-opacity:1"
@ -228,7 +234,7 @@
         sodipodi:role="line"
         id="tspan8"
         x="241.88585"
-         y="126.91018"></tspan></text>
+         y="126.91018" /></text>
    <text
       xml:space="preserve"
       style="font-weight:600;font-size:7.40833px;line-height:0;font-family:'Open Sans';-inkscape-font-specification:'Open Sans, Semi-Bold';text-align:end;writing-mode:lr-tb;direction:ltr;text-anchor:end;fill:#000000;stroke:#241212;stroke-width:0.2;stroke-linejoin:bevel;stroke-opacity:1"
@ -296,18 +302,18 @@
         y="265.51187">Error</tspan></text>
    <path
       style="fill:none;stroke:#241212;stroke-width:0.6;stroke-linejoin:bevel;stroke-dasharray:none;stroke-opacity:1"
-       d="m 148,250.00001 v 20 h 66.99999 l 0,-20"
+       d="m 148,255.82088 v 20 h 66.99999 v -20"
       id="path6"
       sodipodi:nodetypes="cccc" />
-    <path
-       style="fill:none;stroke:#241212;stroke-width:0.6;stroke-linejoin:bevel;stroke-dasharray:none;stroke-opacity:1"
-       d="m 114.50001,250.00001 v 20 H 148 v -20"
-       id="path6-6"
-       sodipodi:nodetypes="cccc" />
    <path
       style="fill:none;stroke:#241212;stroke-width:0.6;stroke-linejoin:bevel;stroke-dasharray:none;stroke-opacity:1"
       d="m 216,172.81966 -0.13385,-22.4101 -101.04619,-0.15132 0.11406,22.56145"
       id="path6-3"
       sodipodi:nodetypes="cccc" />
+    <path
+       style="fill:none;stroke:#422020;stroke-width:0.6;stroke-linejoin:bevel;stroke-dasharray:none;stroke-opacity:1"
+       d="m 115,244.00001 v 3 h 104.99999 c -0.0471,0.12248 0,-37.00001 0,-37.00001 h -3"
+       id="path6-3-7"
+       sodipodi:nodetypes="ccccc" />
  </g>
 </svg>
--- a/include/mqtt_client.h
+++ b/include/mqtt_client.h
@ -94,6 +94,14 @@ private:
    // Verbindungsaufbau (blockierend - NUR aus MQTT-Task auf Core 0 aufrufen!)
    bool reconnect();

+    // TLS-Client komplett abreissen und neu aufbauen (Fix: Heap-Korruption bei
+    // unerwartetem SSL-Verbindungsabbruch durch kaputten mbedTLS-Kontext)
+    void _rebuildClient();
+
+    // Gecachte Broker-Einstellungen fuer _rebuildClient()
+    char     _broker[64];
+    uint16_t _port;
+
    // Heartbeat-Publish (lasercutter/status)
    void publishHeartbeat();

--- a/platformio.ini
+++ b/platformio.ini
@ -23,7 +23,7 @@ build_flags =
    -DCORE_DEBUG_LEVEL=1       ; 0=keine, 1=Fehler, 3=Info, 5=Verbose
    -DARDUINO_LOOP_STACK_SIZE=8192
    -DELEGANTOTA_USE_ASYNC_WEBSERVER=1
-    -DFIRMWARE_VERSION='"1.4.0"' ; Semantic Versioning – hier erhöhen bei neuem Release
+    -DFIRMWARE_VERSION='"1.4.1"' ; Semantic Versioning – hier erhöhen bei neuem Release
 lib_deps =
    majicDesigns/MD_Parola @ ^3.7.3
    majicDesigns/MD_MAX72XX @ ^3.5.1
--- a/src/mqtt_client.cpp
+++ b/src/mqtt_client.cpp
@ -46,6 +46,8 @@ MqttClient::MqttClient()
 {
    _clientId[0]      = '\0';
    _resetReason[0]   = '\0';
+    _broker[0]        = '\0';
+    _port             = 0;
 }

 // --------------------------------------------------------------------------
@ -200,6 +202,43 @@ void MqttClient::publishHeartbeat() {
    LOG_I("MQTT", "Heartbeat: %s -> %s", buf, ok ? "OK" : "FEHLER");
 }

+// --------------------------------------------------------------------------
+// _rebuildClient() - TLS-Client sauber abreissen und neu aufbauen
+// MUSS auf Core 0 aufgerufen werden (mbedtls Heap-Kontext-Binding)
+// --------------------------------------------------------------------------
+void MqttClient::_rebuildClient() {
+    // Alten Client sauber schliessen und freigeben
+    if (_client) {
+        _client->disconnect();
+        delete _client;
+        _client = nullptr;
+    }
+    if (_secureClient) {
+        delete _secureClient;
+        _secureClient = nullptr;
+    }
+    if (_wifiClient) {
+        delete _wifiClient;
+        _wifiClient = nullptr;
+    }
+
+    // Frische Objekte auf Core 0 anlegen
+    _wifiClient   = new WiFiClient();
+    _secureClient = new WiFiClientSecure();
+
+    if (_port == 8883) {
+        _secureClient->setInsecure();
+        _client = new PubSubClient(*_secureClient);
+    } else {
+        _client = new PubSubClient(*_wifiClient);
+    }
+    _client->setServer(_broker, _port);
+    _client->setCallback(MqttClient::onMessage);
+    _client->setKeepAlive(60);
+    _client->setBufferSize(512);
+    LOG_I("MQTT", "Client neu aufgebaut (sauberer TLS-Kontext)");
+}
+
 // --------------------------------------------------------------------------
 // reconnect() - Verbindungsaufbau, non-blocking
 // --------------------------------------------------------------------------
@ -255,6 +294,11 @@ void MqttClient::_taskLoop() {
    const char* broker = cfg.mqttBroker[0] != '\0' ? cfg.mqttBroker : DEFAULT_MQTT_BROKER;
    uint16_t    port   = cfg.mqttPort > 0           ? cfg.mqttPort   : DEFAULT_MQTT_PORT;

+    // Broker/Port für _rebuildClient() sichern
+    strncpy(_broker, broker, sizeof(_broker) - 1);
+    _broker[sizeof(_broker) - 1] = '\0';
+    _port = port;
+
    // Netzwerk-Objekte auf Core 0 anlegen (mbedtls/WiFiClientSecure bindet
    // Heap-Kontexte an den erstellenden Task/Core -> kein Cross-Core-Zugriff).
    _wifiClient   = new WiFiClient();
@ -284,6 +328,9 @@ void MqttClient::_taskLoop() {
            uint32_t now = millis();
            if (now - _lastReconnectMs >= MQTT_RECONNECT_MS) {
                _lastReconnectMs = now;
+                // Sicherstellen, dass kein korrupter mbedTLS-Kontext vom letzten
+                // Verbindungsabbruch uebrig bleibt (Fix FR-011: Heap-Korruption)
+                _rebuildClient();
                reconnect();  // blockiert hier (TLS); Core 1 laeuft unbehelligt
            }
            vTaskDelay(pdMS_TO_TICKS(200));