Issue #10451: memoryview objects could allow to mutate a readable buffer.

Initial patch by Ross Lagerwall.

2 files changed, 15 insertions, 1 deletions

diff --git a/Lib/test/test_getargs2.py b/Lib/test/test_getargs2.py
index e8f4fc2..3d9c06a 100644
--- a/Lib/test/test_getargs2.py
+++ b/Lib/test/test_getargs2.py
@@ -381,8 +381,10 @@ class Bytes_TestCase(unittest.TestCase):
         self.assertRaises(TypeError, getargs_w_star, 'abc\xe9')
         self.assertRaises(TypeError, getargs_w_star, b'bytes')
         self.assertRaises(TypeError, getargs_w_star, b'nul:\0')
+        self.assertRaises(TypeError, getargs_w_star, memoryview(b'bytes'))
         self.assertEqual(getargs_w_star(bytearray(b'bytearray')), b'[ytearra]')
-        self.assertEqual(getargs_w_star(memoryview(b'memoryview')), b'[emoryvie]')
+        self.assertEqual(getargs_w_star(memoryview(bytearray(b'memoryview'))),
+                         b'[emoryvie]')
         self.assertRaises(TypeError, getargs_w_star, None)
 
 
diff --git a/Lib/test/test_memoryview.py b/Lib/test/test_memoryview.py
index 9a52fe90..0bfddd9 100644
--- a/Lib/test/test_memoryview.py
+++ b/Lib/test/test_memoryview.py
@@ -9,6 +9,7 @@ import sys
 import gc
 import weakref
 import array
+import io
 
 
 class AbstractMemoryTests:
@@ -271,6 +272,17 @@ class AbstractMemoryTests:
             m.release()
             self._check_released(m, tp)
 
+    def test_writable_readonly(self):
+        # Issue #10451: memoryview incorrectly exposes a readonly
+        # buffer as writable causing a segfault if using mmap
+        tp = self.ro_type
+        if tp is None:
+            return
+        b = tp(self._source)
+        m = self._view(b)
+        i = io.BytesIO(b'ZZZZ')
+        self.assertRaises(TypeError, i.readinto, m)
+
 # Variations on source objects for the buffer: bytes-like objects, then arrays
 # with itemsize > 1.
 # NOTE: support for multi-dimensional objects is unimplemented.