GH-128563: Don't leave frame->lltrace uninitialized (GH-129417)

Author: brandtbucher

Include/internal/pycore_frame.h

@@ -215,6 +215,9 @@ _PyFrame_Initialize(
     frame->return_offset = 0;
     frame->owner = FRAME_OWNED_BY_THREAD;
     frame->visited = 0;
+#ifdef Py_DEBUG
+    frame->lltrace = 0;
+#endif
 
     for (int i = null_locals_from; i < code->co_nlocalsplus; i++) {
         frame->localsplus[i] = PyStackRef_NULL;
@@ -398,6 +401,9 @@ _PyFrame_PushTrampolineUnchecked(PyThreadState *tstate, PyCodeObject *code, int
 #endif
     frame->owner = FRAME_OWNED_BY_THREAD;
     frame->visited = 0;
+#ifdef Py_DEBUG
+    frame->lltrace = 0;
+#endif
     frame->return_offset = 0;
 
 #ifdef Py_GIL_DISABLED

Misc/NEWS.d/next/Core_and_Builtins/2025-01-28-11-13-41.gh-issue-128563.xElppE.rst

@@ -0,0 +1,2 @@
+Fix an issue where the "lltrace" debug feature could have been incorrectly
+enabled for some frames.