[3.15] gh-151905: fix memory error handling in PyFrame_GetBack (GH-151906) (#151919)

miss-islington · prakashsellathurai · web-flow · commit fe5dc86f1f8a · 2026-06-23T09:28:59.000+03:00
Co-authored-by: Prakash Sellathurai &lt;prakashsellathurai@gmail.com&gt;
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-06-22-06-26-34.gh-issue-151905.FOLMYg.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-06-22-06-26-34.gh-issue-151905.FOLMYg.rst
@@ -0,0 +1 @@
+Fix OOM error handling in :c:func:`PyFrame_GetBack` to propagate exceptions instead of masking them as None.
diff --git a/Objects/frameobject.c b/Objects/frameobject.c
@@ -1117,7 +1117,7 @@ frame_back_get_impl(PyFrameObject *self)
 /*[clinic end generated code: output=3a84c22a55a63c79 input=9e528570d0e1f44a]*/
 {
     PyObject *res = (PyObject *)PyFrame_GetBack(self);
-    if (res == NULL) {
+    if (res == NULL && !PyErr_Occurred()) {
         Py_RETURN_NONE;
     }
     return res;
@@ -2405,6 +2405,9 @@ PyFrame_GetBack(PyFrameObject *frame)
         prev = _PyFrame_GetFirstComplete(prev);
         if (prev) {
             back = _PyFrame_GetFrameObject(prev);
+            if (back == NULL) {
+                return NULL;
+            }
         }
     }
     return (PyFrameObject*)Py_XNewRef(back);

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	+Fix OOM error handling in :c:func:`PyFrame_GetBack` to propagate exceptions instead of masking them as None.
Original file line number	Diff line number	Diff line change
`@@ -1117,7 +1117,7 @@ frame_back_get_impl(PyFrameObject *self)`
`1117`	`1117`	`/[clinic end generated code: output=3a84c22a55a63c79 input=9e528570d0e1f44a]/`
`1118`	`1118`	`{`
`1119`	`1119`	`PyObject res = (PyObject )PyFrame_GetBack(self);`
`1120`		`- if (res == NULL) {`
	`1120`	`+ if (res == NULL && !PyErr_Occurred()) {`
`1121`	`1121`	`Py_RETURN_NONE;`
`1122`	`1122`	`}`
`1123`	`1123`	`return res;`
`@@ -2405,6 +2405,9 @@ PyFrame_GetBack(PyFrameObject *frame)`
`2405`	`2405`	`prev = _PyFrame_GetFirstComplete(prev);`
`2406`	`2406`	`if (prev) {`
`2407`	`2407`	`back = _PyFrame_GetFrameObject(prev);`
	`2408`	`+ if (back == NULL) {`
	`2409`	`+ return NULL;`
	`2410`	`+ }`
`2408`	`2411`	`}`
`2409`	`2412`	`}`
`2410`	`2413`	`return (PyFrameObject*)Py_XNewRef(back);`