Issue #8734: Avoid crash in msvcrt.get_osfhandle() when an invalid file

descriptor is provided.  Patch by Pascal Chambon.

Lib/test/test_fileio.py

@@ -309,6 +309,9 @@ class OtherFileTests(unittest.TestCase):
     def testInvalidFd(self):
         self.assertRaises(ValueError, _FileIO, -10)
         self.assertRaises(OSError, _FileIO, make_bad_fd())
+        if sys.platform == 'win32':
+            import msvcrt
+            self.assertRaises(IOError, msvcrt.get_osfhandle, make_bad_fd())
 
     def testBadModeArgument(self):
         # verify that we get a sensible error message for bad mode argument

Misc/NEWS

@@ -100,6 +100,9 @@ Core and Builtins
 Extensions
 ----------
 
+- Issue #8734: Avoid crash in msvcrt.get_osfhandle() when an invalid file
+  descriptor is provided.  Patch by Pascal Chambon.
+
 - Issue #7736: Release the GIL around calls to opendir() and closedir()
   in the posix module.  Patch by Marcin Bachry.
 

PC/msvcrtmodule.c

@@ -143,6 +143,9 @@ msvcrt_get_osfhandle(PyObject *self, PyObject *args)
     if (!PyArg_ParseTuple(args,"i:get_osfhandle", &fd))
         return NULL;
 
+    if (!_PyVerify_fd(fd))
+        return PyErr_SetFromErrno(PyExc_IOError);
+
     handle = _get_osfhandle(fd);
     if (handle == -1)
         return PyErr_SetFromErrno(PyExc_IOError);