bpo-46090: Allow PyThreadState.datastack_* members to be NULL (GH-30234)

1 files changed, 7 insertions, 4 deletions

diff --git a/Include/internal/pycore_frame.h b/Include/internal/pycore_frame.h
index 883bef1..8eca39d 100644
--- a/Include/internal/pycore_frame.h
+++ b/Include/internal/pycore_frame.h
@@ -174,10 +174,13 @@ static inline InterpreterFrame *
 _PyThreadState_BumpFramePointer(PyThreadState *tstate, size_t size)
 {
     PyObject **base = tstate->datastack_top;
-    PyObject **top = base + size;
-    if (top < tstate->datastack_limit) {
-        tstate->datastack_top = top;
-        return (InterpreterFrame *)base;
+    if (base) {
+        PyObject **top = base + size;
+        assert(tstate->datastack_limit);
+        if (top < tstate->datastack_limit) {
+            tstate->datastack_top = top;
+            return (InterpreterFrame *)base;
+        }
     }
     return _PyThreadState_BumpFramePointerSlow(tstate, size);
 }