Stack overflow checking dysfunctional with USE_STACKCHECK

Python/ceval.c

 
 /* Execute compiled code */
 
 /* XXX TO DO:
    XXX speed up searching for keywords by using a dictionary
    XXX document it!
    */
 
 /* enable more aggressive intra-module optimizations, where available */
 #define PY_LOCAL_AGGRESSIVE
@@ skipping 453 matching lines @@
 {
         PyThreadState *tstate = PyThreadState_GET();
 
 #ifdef USE_STACKCHECK
         if (PyOS_CheckStack()) {
                 --tstate->recursion_depth;
                 PyErr_SetString(PyExc_MemoryError, "Stack overflow");
                 return -1;
         }
 #endif
+        _Py_CheckRecursionLimit = recursion_limit;
         if (tstate->recursion_critical)
                 /* Somebody asked that we don't check for recursion. */
                 return 0;
         if (tstate->overflowed) {
                 if (tstate->recursion_depth > recursion_limit + 50) {
                         /* Overflowing while handling an overflow. Give up. */
                         Py_FatalError("Cannot recover from stack overflow.");
                 }
                 return 0;
         }
         if (tstate->recursion_depth > recursion_limit) {
                 --tstate->recursion_depth;
                 tstate->overflowed = 1;
                 PyErr_Format(PyExc_RuntimeError,
                              "maximum recursion depth exceeded%s",
                              where);
                 return -1;
         }
-        _Py_CheckRecursionLimit = recursion_limit;
         return 0;
 }
 
 /* Status code for main loop (reason for stack unwind) */
 enum why_code {
                 WHY_NOT =       0x0001, /* No error */
                 WHY_EXCEPTION = 0x0002, /* Exception occurred */
                 WHY_RERAISE =   0x0004, /* Exception re-raised by 'finally' */
                 WHY_RETURN =    0x0008, /* 'return' statement */
                 WHY_BREAK =     0x0010, /* 'break' statement */
@@ skipping 3496 matching lines @@
                         Py_DECREF(l);
                         return NULL;
                 }
                 PyList_SetItem(l, i, x);
         }
         return l;
 #endif
 }
 
 #endif