gh-151905: fix memory error handling in PyFrame_GetBack (#151906)

prakashsellathurai · web-flow · commit 1ab8862ea0ad · 2026-06-22T16:41:31.000+05:30
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
@@ -1114,7 +1114,7 @@ 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;
@@ -2402,6 +2402,9 @@ 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
`@@ -1114,7 +1114,7 @@ frame_back_get_impl(PyFrameObject *self)`
`1114`	`1114`	`/[clinic end generated code: output=3a84c22a55a63c79 input=9e528570d0e1f44a]/`
`1115`	`1115`	`{`
`1116`	`1116`	`PyObject res = (PyObject )PyFrame_GetBack(self);`
`1117`		`- if (res == NULL) {`
	`1117`	`+ if (res == NULL && !PyErr_Occurred()) {`
`1118`	`1118`	`Py_RETURN_NONE;`
`1119`	`1119`	`}`
`1120`	`1120`	`return res;`
`@@ -2402,6 +2402,9 @@ PyFrame_GetBack(PyFrameObject *frame)`
`2402`	`2402`	`prev = _PyFrame_GetFirstComplete(prev);`
`2403`	`2403`	`if (prev) {`
`2404`	`2404`	`back = _PyFrame_GetFrameObject(prev);`
	`2405`	`+ if (back == NULL) {`
	`2406`	`+ return NULL;`
	`2407`	`+ }`
`2405`	`2408`	`}`
`2406`	`2409`	`}`
`2407`	`2410`	`return (PyFrameObject*)Py_XNewRef(back);`