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gh-148144: Initialize visited on copied interpreter frames #148143

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pablogsal merged 1 commit into from
Apr 5, 2026
+8 −0
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gh-148144: Initialize visited on copied interpreter frames #148143

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5 changes: 5 additions & 0 deletions Include/internal/pycore_interpframe.h
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Original file line number Diff line number Diff line change
Expand Up @@ -149,6 +149,11 @@ static inline void _PyFrame_Copy(_PyInterpreterFrame *src, _PyInterpreterFrame *
int stacktop = (int)(src->stackpointer - src->localsplus);
assert(stacktop >= 0);
dest->stackpointer = dest->localsplus + stacktop;
// visited is GC bookkeeping for the current stack walk, not frame state.
dest->visited = 0;
#ifdef Py_DEBUG
dest->lltrace = src->lltrace;
#endif
for (int i = 0; i < stacktop; i++) {
dest->localsplus[i] = PyStackRef_MakeHeapSafe(src->localsplus[i]);
}
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2026-04-05-15-20-00.gh-issue-148144.f7qA0x.rst
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@@ -0,0 +1,3 @@
Initialize ``_PyInterpreterFrame.visited`` when copying interpreter frames so
incremental GC does not read an uninitialized byte from generator and
frame-object copies.
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