[Python-checkins] bpo-33720: Reduces maximum marshal recursion depth on release builds. (GH-7401)

[Steve Dower]

https://github.com/python/cpython/commit/2a4a62ba4ae770bbc7b7fdec0760031c83fe1f7b
commit: 2a4a62ba4ae770bbc7b7fdec0760031c83fe1f7b
branch: master
author: Steve Dower <steve.dower at microsoft.com>
committer: GitHub <noreply at github.com>
date: 2018-06-04T13:25:00-07:00
summary:

bpo-33720: Reduces maximum marshal recursion depth on release builds. (GH-7401)

files:
A Misc/NEWS.d/next/Windows/2018-06-04-09-20-53.bpo-33720.VKDXHK.rst
M Lib/test/test_marshal.py
M Python/marshal.c

diff --git a/Lib/test/test_marshal.py b/Lib/test/test_marshal.py
index 29dda987d0bb..a8a43d22bc36 100644
--- a/Lib/test/test_marshal.py
+++ b/Lib/test/test_marshal.py
@@ -222,7 +222,10 @@ def test_recursion_limit(self):
         # Create a deeply nested structure.
         head = last = []
         # The max stack depth should match the value in Python/marshal.c.
-        if os.name == 'nt' and hasattr(sys, 'gettotalrefcount'):
+        # BUG: https://bugs.python.org/issue33720
+        # Windows always limits the maximum depth on release and debug builds
+        #if os.name == 'nt' and hasattr(sys, 'gettotalrefcount'):
+        if os.name == 'nt':
             MAX_MARSHAL_STACK_DEPTH = 1000
         else:
             MAX_MARSHAL_STACK_DEPTH = 2000
diff --git a/Misc/NEWS.d/next/Windows/2018-06-04-09-20-53.bpo-33720.VKDXHK.rst b/Misc/NEWS.d/next/Windows/2018-06-04-09-20-53.bpo-33720.VKDXHK.rst
new file mode 100644
index 000000000000..f7e2f9d1eae4
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2018-06-04-09-20-53.bpo-33720.VKDXHK.rst
@@ -0,0 +1 @@
+Reduces maximum marshal recursion depth on release builds.
diff --git a/Python/marshal.c b/Python/marshal.c
index e23daf6497b4..6d06266c6a8e 100644
--- a/Python/marshal.c
+++ b/Python/marshal.c
@@ -25,8 +25,14 @@ module marshal
  * and risks coring the interpreter.  When the object stack gets this deep,
  * raise an exception instead of continuing.
  * On Windows debug builds, reduce this value.
+ *
+ * BUG: https://bugs.python.org/issue33720
+ * On Windows PGO builds, the r_object function overallocates its stack and
+ * can cause a stack overflow. We reduce the maximum depth for all Windows
+ * releases to protect against this.
+ * #if defined(MS_WINDOWS) && defined(_DEBUG)
  */
-#if defined(MS_WINDOWS) && defined(_DEBUG)
+#if defined(MS_WINDOWS)
 #define MAX_MARSHAL_STACK_DEPTH 1000
 #else
 #define MAX_MARSHAL_STACK_DEPTH 2000