From: Daniel Li <daniel.li@deshaw.com>
Date: Fri, 23 May 2025 18:45:45 +0000 (-0400)
Subject: gh-120170: Exclude __mp_main__ in C version of whichmodule() (#120171)
X-Git-Tag: v3.15.0a1~1545
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=05a19b5e56894fd1e63aff6b38fb23ad7c7b3047;p=thirdparty%2FPython%2Fcpython.git

gh-120170: Exclude __mp_main__ in C version of whichmodule() (#120171)

Co-authored-by: Lysandros Nikolaou <lisandrosnik@gmail.com>
---

diff --git a/Misc/NEWS.d/next/Library/2024-06-06-17-49-07.gh-issue-120170.DUxhmT.rst b/Misc/NEWS.d/next/Library/2024-06-06-17-49-07.gh-issue-120170.DUxhmT.rst
new file mode 100644
index 000000000000..ce7d874aa203
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-06-06-17-49-07.gh-issue-120170.DUxhmT.rst
@@ -0,0 +1,3 @@
+Fix an issue in the :mod:`!_pickle` extension module in which importing
+:mod:`multiprocessing` could change how pickle identifies which module an
+object belongs to, potentially breaking the unpickling of those objects.
diff --git a/Modules/_pickle.c b/Modules/_pickle.c
index d260f1a68f8c..29ef0cb0c2e0 100644
--- a/Modules/_pickle.c
+++ b/Modules/_pickle.c
@@ -1879,6 +1879,10 @@ _checkmodule(PyObject *module_name, PyObject *module,
             _PyUnicode_EqualToASCIIString(module_name, "__main__")) {
         return -1;
     }
+    if (PyUnicode_Check(module_name) &&
+            _PyUnicode_EqualToASCIIString(module_name, "__mp_main__")) {
+        return -1;
+    }
 
     PyObject *candidate = getattribute(module, dotted_path, 0);
     if (candidate == NULL) {