[3.6] bpo-33263: Fix FD leak in _SelectorSocketTransport (GH-6450) (#7025)

asvetlov · web-flow · commit 7208bfb64b74 · 2018-05-21T13:09:49.000+03:00
* bpo-33263 Fix FD leak in _SelectorSocketTransport. (GH-6450) Under particular circumstances _SelectorSocketTransport can try to add a reader even the transport is already being closed. This can lead to FD leak and invalid stated of the following connections. Fixed the SelectorSocketTransport to add the reader only if the trasport is still active.. (cherry picked from commit a84d0b3)
diff --git a/Lib/asyncio/selector_events.py b/Lib/asyncio/selector_events.py
@@ -673,6 +673,12 @@ def _call_connection_lost(self, exc):
     def get_write_buffer_size(self):
         return len(self._buffer)
 
+    def _add_reader(self, fd, callback, *args):
+        if self._closing:
+            return
+
+        self._loop._add_reader(fd, callback, *args)
+
 
 class _SelectorSocketTransport(_SelectorTransport):
 
@@ -689,7 +695,7 @@ def __init__(self, loop, sock, protocol, waiter=None,
 
         self._loop.call_soon(self._protocol.connection_made, self)
         # only start reading when connection_made() has been called
-        self._loop.call_soon(self._loop._add_reader,
+        self._loop.call_soon(self._add_reader,
                              self._sock_fd, self._read_ready)
         if waiter is not None:
             # only wake up the waiter when connection_made() has been called
@@ -710,9 +716,7 @@ def resume_reading(self):
         if not self._paused:
             raise RuntimeError('Not paused')
         self._paused = False
-        if self._closing:
-            return
-        self._loop._add_reader(self._sock_fd, self._read_ready)
+        self._add_reader(self._sock_fd, self._read_ready)
         if self._loop.get_debug():
             logger.debug("%r resumes reading", self)
 
@@ -1052,7 +1056,7 @@ def __init__(self, loop, sock, protocol, address=None,
         self._address = address
         self._loop.call_soon(self._protocol.connection_made, self)
         # only start reading when connection_made() has been called
-        self._loop.call_soon(self._loop._add_reader,
+        self._loop.call_soon(self._add_reader,
                              self._sock_fd, self._read_ready)
         if waiter is not None:
             # only wake up the waiter when connection_made() has been called
diff --git a/Lib/test/test_asyncio/test_selector_events.py b/Lib/test/test_asyncio/test_selector_events.py
@@ -832,6 +832,21 @@ def test_connection_lost(self):
         self.assertIsNone(tr._protocol)
         self.assertIsNone(tr._loop)
 
+    def test__add_reader(self):
+        tr = self.create_transport()
+        tr._buffer.extend(b'1')
+        tr._add_reader(7, mock.sentinel)
+        self.assertTrue(self.loop.readers)
+
+        tr._force_close(None)
+
+        self.assertTrue(tr.is_closing())
+        self.assertFalse(self.loop.readers)
+
+        # can not add readers after closing
+        tr._add_reader(7, mock.sentinel)
+        self.assertFalse(self.loop.readers)
+
 
 class SelectorSocketTransportTests(test_utils.TestCase):
 
diff --git a/Misc/NEWS.d/next/Library/2018-04-11-20-29-19.bpo-33263.B56Hc1.rst b/Misc/NEWS.d/next/Library/2018-04-11-20-29-19.bpo-33263.B56Hc1.rst
@@ -0,0 +1 @@
+Fix FD leak in `_SelectorSocketTransport`  Patch by Vlad Starostin.

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	+Fix FD leak in `_SelectorSocketTransport` Patch by Vlad Starostin.