check windows fd validity (closes #16992)

Lib/test/test_signal.py

@@ -222,6 +222,13 @@ class WindowsSignalTests(unittest.TestCase):
             signal.signal(7, handler)
 
 
+class WakeupFDTests(unittest.TestCase):
+
+    def test_invalid_fd(self):
+        fd = support.make_bad_fd()
+        self.assertRaises(ValueError, signal.set_wakeup_fd, fd)
+
+
 @unittest.skipIf(sys.platform == "win32", "Not valid on Windows")
 class WakeupSignalTests(unittest.TestCase):
     def check_wakeup(self, test_body, *signals, ordered=True):
@@ -864,8 +871,8 @@ class PendingSignalsTests(unittest.TestCase):
 def test_main():
     try:
         support.run_unittest(PosixTests, InterProcessSignalTests,
-                             WakeupSignalTests, SiginterruptTest,
-                             ItimerTest, WindowsSignalTests,
+                             WakeupFDTests, WakeupSignalTests,
+                             SiginterruptTest, ItimerTest, WindowsSignalTests,
                              PendingSignalsTests)
     finally:
         support.reap_children()

Misc/NEWS

@@ -150,6 +150,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #16992: On Windows in signal.set_wakeup_fd, validate the file
+  descriptor argument.
+
 - Issue #16422: For compatibility with the Python version, the C version of
   decimal now uses strings instead of integers for rounding mode constants.
 

Modules/signalmodule.c

@@ -427,7 +427,7 @@ signal_set_wakeup_fd(PyObject *self, PyObject *args)
         return NULL;
     }
 #endif
-    if (fd != -1 && fstat(fd, &buf) != 0) {
+    if (fd != -1 && (!_PyVerify_fd(fd) || fstat(fd, &buf) != 0)) {
         PyErr_SetString(PyExc_ValueError, "invalid fd");
         return NULL;
     }