[core] Fix use-after-free when deleting a running StaticTask (#19048)

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

esphome/components/micro_wake_word/micro_wake_word.cpp

@@ -446,9 +446,9 @@ void MicroWakeWord::loop() {
     xEventGroupClearBits(this->event_group_, EventGroupBits::TASK_STOPPING);
   }
 
-  if ((event_group_bits & EventGroupBits::TASK_STOPPED)) {
+  // Retries on a subsequent loop if the task is still running on the other core
+  if ((event_group_bits & EventGroupBits::TASK_STOPPED) && this->inference_task_.deallocate()) {
     ESP_LOGD(TAG, "Inference task is finished, freeing task resources");
-    this->inference_task_.deallocate();
     xEventGroupClearBits(this->event_group_, ALL_BITS);
     xQueueReset(this->detection_queue_);
     this->set_state_(State::STOPPED);

esphome/components/mixer/speaker/mixer_speaker.cpp

@@ -382,8 +382,8 @@ void MixerSpeaker::loop() {
     ESP_LOGV(TAG, "Stopping");
     xEventGroupClearBits(this->event_group_, MIXER_TASK_STATE_STOPPING);
   }
-  if (event_group_bits & MIXER_TASK_STATE_STOPPED) {
-    this->task_.deallocate();
+  // Retries on a subsequent loop if the task is still running on the other core
+  if ((event_group_bits & MIXER_TASK_STATE_STOPPED) && this->task_.deallocate()) {
     ESP_LOGD(TAG, "Stopped");
     xEventGroupClearBits(this->event_group_, MIXER_TASK_ALL_BITS);
     this->all_stopped_since_ms_ = 0;

esphome/components/resampler/speaker/resampler_speaker.cpp

@@ -153,8 +153,8 @@ void ResamplerSpeaker::loop() {
     ESP_LOGV(TAG, "Stopping");
     xEventGroupClearBits(this->event_group_, ResamplingEventGroupBits::STATE_STOPPING);
   }
-  if (event_group_bits & ResamplingEventGroupBits::STATE_STOPPED) {
-    this->task_.deallocate();
+  // Retries on a subsequent loop if the task is still running on the other core
+  if ((event_group_bits & ResamplingEventGroupBits::STATE_STOPPED) && this->task_.deallocate()) {
     ESP_LOGD(TAG, "Stopped");
     xEventGroupClearBits(this->event_group_, ResamplingEventGroupBits::ALL_BITS);
   }

esphome/components/speaker/media_player/audio_pipeline.cpp

@@ -202,8 +202,15 @@ AudioPipelineState AudioPipeline::process_state() {
     if (!this->is_playing_) {
       // The tasks have been stopped for two ``process_state`` calls in a row, so delete the tasks
       if (this->read_task_.is_created() || this->decode_task_.is_created()) {
-        this->read_task_.deallocate();
-        this->decode_task_.deallocate();
+        // Both are attempted every time; a task that is still running on the other core is freed by a
+        // subsequent call, and freeing an already freed task succeeds without doing anything
+        bool read_task_freed = this->read_task_.deallocate();
+        bool decode_task_freed = this->decode_task_.deallocate();
+        if (!read_task_freed || !decode_task_freed) {
+          // A task is still running on the other core, so keep the pipeline in its current state and try
+          // again on the next call
+          return AudioPipelineState::PLAYING;
+        }
         if (this->hard_stop_) {
           // Stop command was sent, so immediately end the playback
           this->speaker_->stop();

esphome/core/static_task.cpp

@@ -40,16 +40,31 @@ bool StaticTask::create(TaskFunction_t fn, const char *name, uint32_t stack_size
   return true;
 }
 
-void StaticTask::destroy() {
-  if (this->handle_ != nullptr) {
-    TaskHandle_t handle = this->handle_;
-    this->handle_ = nullptr;
-    vTaskDelete(handle);
+bool StaticTask::destroy() {
+  if (this->handle_ == nullptr) {
+    return true;
   }
+
+  // Suspending takes the task off the ready and event lists, so nothing can schedule it again. It only asks
+  // the other core to yield though, so the task may still be running on it for a moment.
+  vTaskSuspend(this->handle_);
+  if (eTaskGetState(this->handle_) != eSuspended) {
+    // The task is still running on the other core and using its stack. Deleting it now would only put it on
+    // the termination list and return, so the caller has to try again once it has been swapped out.
+    return false;
+  }
+
+  // The task cannot run again, so the delete completes right away instead of being left to the idle task.
+  TaskHandle_t handle = this->handle_;
+  this->handle_ = nullptr;
+  vTaskDelete(handle);
+  return true;
 }
 
-void StaticTask::deallocate() {
-  this->destroy();
+bool StaticTask::deallocate() {
+  if (!this->destroy()) {
+    return false;
+  }
   if (this->stack_buffer_ != nullptr) {
     RAMAllocator<StackType_t> allocator(this->use_psram_ ? RAMAllocator<StackType_t>::ALLOC_EXTERNAL
                                                          : RAMAllocator<StackType_t>::ALLOC_INTERNAL);
@@ -57,6 +72,7 @@ void StaticTask::deallocate() {
     this->stack_buffer_ = nullptr;
     this->stack_size_ = 0;
   }
+  return true;
 }
 
 }  // namespace esphome

esphome/core/static_task.h

@@ -11,6 +11,7 @@ namespace esphome {
 
 /** Helper for FreeRTOS static task management.
  * Bundles TaskHandle_t, StaticTask_t, and the stack buffer into one object with create/destroy methods.
+ * Call destroy() and deallocate() from another task: a task cannot free the stack it is still running on.
  */
 class StaticTask {
  public:
@@ -23,7 +24,7 @@ class StaticTask {
   /// @brief Allocate stack and create task.
   /// @param fn         Task function
   /// @param name       Task name (for debug)
-  /// @param stack_size Stack size in StackType_t words
+  /// @param stack_size Stack size in bytes (StackType_t is a byte on ESP-IDF)
   /// @param param      Parameter passed to task function
   /// @param priority   FreeRTOS task priority
   /// @param use_psram  If true, allocate stack in PSRAM; otherwise internal RAM
@@ -31,11 +32,17 @@ class StaticTask {
   bool create(TaskFunction_t fn, const char *name, uint32_t stack_size, void *param, UBaseType_t priority,
               bool use_psram);
 
-  /// @brief Delete the task but keep the stack buffer allocated for reuse by a subsequent create() call.
-  void destroy();
+  /// @brief Delete the task, keeping the stack buffer allocated for reuse by a subsequent create() call.
+  /// The task must have finished its work and parked itself, either suspended or blocked indefinitely: it is
+  /// suspended here so that it cannot be scheduled again, and it is given no chance to clean up.
+  /// @return true if the task was deleted; false if it is still running on another core, in which case the
+  /// caller should try again later.
+  bool destroy();
 
-  /// @brief Delete the task (if running) and free the stack buffer.
-  void deallocate();
+  /// @brief Delete the task (if created) and free the stack buffer.
+  /// @return true if the stack buffer was freed; false if the task is still running on another core, in
+  /// which case the caller should try again later.
+  bool deallocate();
 
  protected:
   TaskHandle_t handle_{nullptr};