From 17065c49fcce5a0b4d0894240902d1782a29857e Mon Sep 17 00:00:00 2001
From: "Erlend E. Aasland" <erlend.aasland@protonmail.com>
Date: Thu, 8 Jun 2023 09:24:49 +0200
Subject: [PATCH 1/3] gh-105375: Improve error handling in
 PyUnicode_BuildEncodingMap()

---
 Objects/unicodeobject.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index ffb4a87d4b9265..f3fc88e011ef13 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -7934,25 +7934,29 @@ PyUnicode_BuildEncodingMap(PyObject* string)
 
     if (need_dict) {
         PyObject *result = PyDict_New();
-        PyObject *key, *value;
         if (!result)
             return NULL;
         for (i = 0; i < length; i++) {
-            key = PyLong_FromLong(PyUnicode_READ(kind, data, i));
-            value = PyLong_FromLong(i);
-            if (!key || !value)
-                goto failed1;
-            if (PyDict_SetItem(result, key, value) == -1)
-                goto failed1;
+            PyObject *key = PyLong_FromLong(PyUnicode_READ(kind, data, i));
+            if (key == NULL) {
+                Py_DECREF(result);
+                return NULL;
+            }
+            PyObject *value = PyLong_FromLong(i);
+            if (value == NULL) {
+                Py_DECREF(key);
+                Py_DECREF(result);
+                return NULL;
+            }
+            int rc = PyDict_SetItem(result, key, value);
             Py_DECREF(key);
             Py_DECREF(value);
+            if (rc < 0) {
+                Py_DECREF(result);
+                return NULL;
+            }
         }
         return result;
-      failed1:
-        Py_XDECREF(key);
-        Py_XDECREF(value);
-        Py_DECREF(result);
-        return NULL;
     }
 
     /* Create a three-level trie */

From a4464137c4cc163f73d537d955e30a62cbc99d51 Mon Sep 17 00:00:00 2001
From: "Erlend E. Aasland" <erlend.aasland@protonmail.com>
Date: Thu, 8 Jun 2023 09:25:57 +0200
Subject: [PATCH 2/3] Add NEWS

---
 .../2023-06-08-09-25-52.gh-issue-105375.ocB7fT.rst              | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2023-06-08-09-25-52.gh-issue-105375.ocB7fT.rst

diff --git a/Misc/NEWS.d/next/Core and Builtins/2023-06-08-09-25-52.gh-issue-105375.ocB7fT.rst b/Misc/NEWS.d/next/Core and Builtins/2023-06-08-09-25-52.gh-issue-105375.ocB7fT.rst
new file mode 100644
index 00000000000000..24fac2df4d0955
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2023-06-08-09-25-52.gh-issue-105375.ocB7fT.rst	
@@ -0,0 +1,2 @@
+Improve error handling in :c:func:`PyUnicode_BuildEncodingMap` where an
+exception could end up being overwritten.

From 94ae5bd7359a93219da3874bc5fe4c96d5fe4e7c Mon Sep 17 00:00:00 2001
From: "Erlend E. Aasland" <erlend.aasland@protonmail.com>
Date: Fri, 9 Jun 2023 21:52:05 +0200
Subject: [PATCH 3/3] Update Objects/unicodeobject.c

---
 Objects/unicodeobject.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index f3fc88e011ef13..38b72de88f3c0b 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -7937,7 +7937,8 @@ PyUnicode_BuildEncodingMap(PyObject* string)
         if (!result)
             return NULL;
         for (i = 0; i < length; i++) {
-            PyObject *key = PyLong_FromLong(PyUnicode_READ(kind, data, i));
+            Py_UCS4 c = PyUnicode_READ(kind, data, i);
+            PyObject *key = PyLong_FromLong(c);
             if (key == NULL) {
                 Py_DECREF(result);
                 return NULL;