From: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com>
Date: Mon, 29 Jun 2026 16:52:04 +0000 (+0200)
Subject: [3.15] gh-152228: Fix an assertion failure in `str.replace` under a limited memory... 
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e08e00383ff92566fb0a14bdf620c3f082bd1443;p=thirdparty%2FPython%2Fcpython.git

[3.15] gh-152228: Fix an assertion failure in `str.replace` under a limited memory case (GH-152229) (#152615)

gh-152228: Fix an assertion failure in `str.replace` under a limited memory case (GH-152229)
(cherry picked from commit c5043dce1c6743682d93c71e937b95e7d27e0b35)

Co-authored-by: sobolevn <mail@sobolevn.me>
---

diff --git a/Lib/test/test_str.py b/Lib/test/test_str.py
index 4f57499af70f..979bfe36fff6 100644
--- a/Lib/test/test_str.py
+++ b/Lib/test/test_str.py
@@ -607,6 +607,21 @@ class StrTest(string_tests.StringLikeTest,
         text = 'abc def'
         self.assertIs(text.replace(pattern, pattern), text)
 
+    @support.nomemtest
+    def test_replace_oom(self):
+        # https://github.com/python/cpython/issues/152228
+        s1 = "轘" * 4
+        s2 = "&"
+        s3 = "&amp;"
+        assertion = self.assertRaises(MemoryError)
+        _testcapi.set_nomemory(0, 0)
+        try:
+            # No allocations made in the test itself:
+            with assertion:
+                s1.replace(s2, s3)  # this line used to crash before
+        finally:
+            _testcapi.remove_mem_hooks()
+
     def test_repeat_id_preserving(self):
         a = '123abc1@'
         b = '456zyx-+'
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-06-25-21-34-15.gh-issue-152228.a6K14K.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-06-25-21-34-15.gh-issue-152228.a6K14K.rst
new file mode 100644
index 000000000000..8af7ae0d1739
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-06-25-21-34-15.gh-issue-152228.a6K14K.rst
@@ -0,0 +1,2 @@
+Fix an assertion failure when python is built in a debug mode
+that happened in :meth:`str.replace` under a limited memory situation.
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 74d6ba4db9f2..18523c2dfde7 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -10753,9 +10753,9 @@ replace(PyObject *self, PyObject *str1,
     }
 
   done:
-    assert(srelease == (sbuf != PyUnicode_DATA(self)));
-    assert(release1 == (buf1 != PyUnicode_DATA(str1)));
-    assert(release2 == (buf2 != PyUnicode_DATA(str2)));
+    assert(srelease == (sbuf != NULL && sbuf != PyUnicode_DATA(self)));
+    assert(release1 == (buf1 != NULL && buf1 != PyUnicode_DATA(str1)));
+    assert(release2 == (buf2 != NULL && buf2 != PyUnicode_DATA(str2)));
     if (srelease)
         PyMem_Free((void *)sbuf);
     if (release1)
@@ -10767,9 +10767,9 @@ replace(PyObject *self, PyObject *str1,
 
   nothing:
     /* nothing to replace; return original string (when possible) */
-    assert(srelease == (sbuf != PyUnicode_DATA(self)));
-    assert(release1 == (buf1 != PyUnicode_DATA(str1)));
-    assert(release2 == (buf2 != PyUnicode_DATA(str2)));
+    assert(srelease == (sbuf != NULL && sbuf != PyUnicode_DATA(self)));
+    assert(release1 == (buf1 != NULL && buf1 != PyUnicode_DATA(str1)));
+    assert(release2 == (buf2 != NULL && buf2 != PyUnicode_DATA(str2)));
     if (srelease)
         PyMem_Free((void *)sbuf);
     if (release1)
@@ -10779,9 +10779,9 @@ replace(PyObject *self, PyObject *str1,
     return unicode_result_unchanged(self);
 
   error:
-    assert(srelease == (sbuf != PyUnicode_DATA(self)));
-    assert(release1 == (buf1 != PyUnicode_DATA(str1)));
-    assert(release2 == (buf2 != PyUnicode_DATA(str2)));
+    assert(srelease == (sbuf != NULL && sbuf != PyUnicode_DATA(self)));
+    assert(release1 == (buf1 != NULL && buf1 != PyUnicode_DATA(str1)));
+    assert(release2 == (buf2 != NULL && buf2 != PyUnicode_DATA(str2)));
     if (srelease)
         PyMem_Free((void *)sbuf);
     if (release1)