From c567883ff5915da6fc8f215b0f1625ba470c7fa1 Mon Sep 17 00:00:00 2001
From: Nils Weiss <nils.weiss@dissecto.com>
Date: Tue, 20 Oct 2026 08:42:18 +0200
Subject: [PATCH] automaton: raise on Windows WAIT_FAILED

ctypes may return WAIT_FAILED as -1, which select_objects() treats as an input index and can report the last object ready. Raise the Windows error and close temporary Winsock events on failed waits.

AI-Assisted: yes (GPT-6)
---
 scapy/automaton.py | 13 ++++++++++++-
 test/windows.uts   | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/scapy/automaton.py b/scapy/automaton.py
index 303db73a38d..9ef4a0aa325 100644
--- a/scapy/automaton.py
+++ b/scapy/automaton.py
@@ -139,7 +139,13 @@ def select_objects(inputs, remain):
                 False,
                 remainms
             )
-        if res != 0xFFFFFFFF and res != 0x00000102:  # Failed or Timeout
+        # ctypes' default signed c_int restype returns WAIT_FAILED as -1.
+        if res == -1 or res == 0xFFFFFFFF:
+            error = ctypes.WinError()
+            for evt in created:
+                ctypes.windll.ws2_32.WSACloseEvent(evt)
+            raise error
+        if res != 0x00000102:  # Timeout
             results.add(inputs[res])
             if len(events) > 1:
                 # Now poll the others, if any
@@ -148,6 +154,11 @@ def select_objects(inputs, remain):
                         ctypes.c_void_p(evt),
                         0  # poll: don't wait
                     )
+                    if res == -1 or res == 0xFFFFFFFF:
+                        error = ctypes.WinError()
+                        for created_evt in created:
+                            ctypes.windll.ws2_32.WSACloseEvent(created_evt)
+                        raise error
                     if res == 0:
                         results.add(inputs[i])
     # Cleanup created events, if any
diff --git a/test/windows.uts b/test/windows.uts
index 394376be0c2..56e2f6f1eba 100644
--- a/test/windows.uts
+++ b/test/windows.uts
@@ -5,6 +5,7 @@
 + Configuration
 
 = Imports
+~ automaton
 
 from unittest import mock
 
@@ -21,6 +22,51 @@ a = ObjectPipe()
 a.send("test")
 assert select_objects([a], 0) == [a]
 
+= Automaton - WaitFor* errors are raised
+~ automaton
+
+import ctypes as _ctypes
+import scapy.automaton as _automaton
+
+for failure, input_count, use_native_socket in [
+        (-1, 1, True),
+        (0xFFFFFFFF, 2, False),
+        (0, 2, True)]:
+    inputs = [mock.Mock() for _ in range(input_count)]
+    for index, obj in enumerate(inputs):
+        obj.fileno.return_value = index + 10
+        obj.__selectable_force_select__ = False
+    if use_native_socket:
+        inputs[0].__selectable_force_select__ = True
+    kernel32 = mock.Mock()
+    if input_count == 1:
+        kernel32.WaitForSingleObject.return_value = failure
+    elif use_native_socket:
+        kernel32.WaitForMultipleObjects.return_value = 0
+        kernel32.WaitForSingleObject.return_value = -1
+    else:
+        kernel32.WaitForMultipleObjects.return_value = failure
+    ws2_32 = mock.Mock()
+    ws2_32.WSACreateEvent.return_value = 100
+    ws2_32.WSAEventSelect.return_value = 0
+    windll = mock.Mock(kernel32=kernel32, ws2_32=ws2_32)
+    with mock.patch.object(_automaton, "WINDOWS", True):
+        with mock.patch.object(_automaton, "ctypes", _ctypes, create=True):
+            with mock.patch.object(
+                    _ctypes, "windll", windll, create=True):
+                with mock.patch.object(
+                        _ctypes, "WinError",
+                        return_value=OSError("wait failed"), create=True
+                ) as win_error:
+                    try:
+                        select_objects(inputs, 0)
+                    except OSError:
+                        pass
+                    else:
+                        assert False, "WAIT_FAILED must raise an OSError"
+    win_error.assert_called_once_with()
+    if use_native_socket:
+        assert ws2_32.WSACloseEvent.call_count == 1
 ############
 ############
 + Windows arch unit tests