diff -r 731b9653ef6b Lib/_pyio.py
--- a/Lib/_pyio.py	Mon Dec 22 22:10:10 2014 +0100
+++ b/Lib/_pyio.py	Tue Dec 23 09:24:59 2014 +0200
@@ -852,8 +852,14 @@ class BytesIO(BufferedIOBase):
     def getbuffer(self):
         """Return a readable and writable view of the buffer.
         """
+        if self.closed:
+            raise ValueError("getbuffer on closed file")
         return memoryview(self._buffer)
 
+    def close(self):
+        self._buffer.clear()
+        super().close()
+
     def read(self, size=None):
         if self.closed:
             raise ValueError("read from closed file")
diff -r 731b9653ef6b Lib/test/test_memoryio.py
--- a/Lib/test/test_memoryio.py	Mon Dec 22 22:10:10 2014 +0100
+++ b/Lib/test/test_memoryio.py	Tue Dec 23 09:24:59 2014 +0200
@@ -399,14 +399,19 @@ class BytesIOMixin:
         # raises a BufferError.
         self.assertRaises(BufferError, memio.write, b'x' * 100)
         self.assertRaises(BufferError, memio.truncate)
+        self.assertRaises(BufferError, memio.close)
+        self.assertFalse(memio.closed)
         # Mutating the buffer updates the BytesIO
         buf[3:6] = b"abc"
         self.assertEqual(bytes(buf), b"123abc7890")
         self.assertEqual(memio.getvalue(), b"123abc7890")
-        # After the buffer gets released, we can resize the BytesIO again
+        # After the buffer gets released, we can resize and close the BytesIO
+        # again
         del buf
         support.gc_collect()
         memio.truncate()
+        memio.close()
+        self.assertRaises(ValueError, memio.getbuffer)
 
 
 class PyBytesIOTest(MemoryTestMixin, MemorySeekTestMixin,
diff -r 731b9653ef6b Misc/NEWS
--- a/Misc/NEWS	Mon Dec 22 22:10:10 2014 +0100
+++ b/Misc/NEWS	Tue Dec 23 09:24:59 2014 +0200
@@ -196,6 +196,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #23099: Closing io.BytesIO with exported buffer is rejected now to
+  prevent corrupting exported buffer.
+
 - Issue #23093: In the io, module allow more operations to work on detached
   streams.
 
diff -r 731b9653ef6b Modules/_io/bytesio.c
--- a/Modules/_io/bytesio.c	Mon Dec 22 22:10:10 2014 +0100
+++ b/Modules/_io/bytesio.c	Tue Dec 23 09:24:59 2014 +0200
@@ -777,6 +777,7 @@ PyDoc_STRVAR(close_doc,
 static PyObject *
 bytesio_close(bytesio *self)
 {
+    CHECK_EXPORTS(self);
     reset(self);
     Py_RETURN_NONE;
 }