Issue #27759: Fix selectors incorrectly retain invalid file descriptors.

(Backported to 3.4 as this bug might be exploited to for DoS)

1 files changed, 23 insertions, 0 deletions

diff --git a/Lib/test/test_selectors.py b/Lib/test/test_selectors.py
index 952fda6..28cd948 100644
--- a/Lib/test/test_selectors.py
+++ b/Lib/test/test_selectors.py
@@ -5,6 +5,7 @@ import selectors
 import signal
 import socket
 import sys
+import tempfile
 from test import support
 from time import sleep
 import unittest
@@ -447,6 +448,16 @@ class EpollSelectorTestCase(BaseSelectorTestCase, ScalableSelectorMixIn):
 
     SELECTOR = getattr(selectors, 'EpollSelector', None)
 
+    def test_register_file(self):
+        # epoll(7) returns EPERM when given a file to watch
+        s = self.SELECTOR()
+        with tempfile.NamedTemporaryFile() as f:
+            with self.assertRaises(IOError):
+                s.register(f, selectors.EVENT_READ)
+            # the SelectorKey has been removed
+            with self.assertRaises(KeyError):
+                s.get_key(f)
+
 
 @unittest.skipUnless(hasattr(selectors, 'KqueueSelector'),
                      "Test needs selectors.KqueueSelector)")
@@ -454,6 +465,18 @@ class KqueueSelectorTestCase(BaseSelectorTestCase, ScalableSelectorMixIn):
 
     SELECTOR = getattr(selectors, 'KqueueSelector', None)
 
+    def test_register_bad_fd(self):
+        # a file descriptor that's been closed should raise an OSError
+        # with EBADF
+        s = self.SELECTOR()
+        bad_f = support.make_bad_fd()
+        with self.assertRaises(OSError) as cm:
+            s.register(bad_f, selectors.EVENT_READ)
+        self.assertEqual(cm.exception.errno, errno.EBADF)
+        # the SelectorKey has been removed
+        with self.assertRaises(KeyError):
+            s.get_key(bad_f)
+
 
 def test_main():
     tests = [DefaultSelectorTestCase, SelectSelectorTestCase,