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bpo-9263: Fix _PyObject_Dump() for freed object (#10661)

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If _PyObject_Dump() detects that the object is freed, don't try to
dump it (exit immediately).

Enhance also _PyObject_IsFreed(): it now detects if the pointer
itself looks like freed memory.
This commit is contained in:
Victor Stinner 2018-11-22 16:32:57 +01:00 • committed by GitHub
parent 9a0d7a7648
commit 2cf5d32fd9
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1 changed files with 5 additions and 0 deletions
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5
Objects/object.c
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@ -423,6 +423,10 @@ _Py_BreakPoint(void)
int int
_PyObject_IsFreed(PyObject *op) _PyObject_IsFreed(PyObject *op)
{ {
uintptr_t ptr = (uintptr_t)op;
if (_PyMem_IsFreed(&ptr, sizeof(ptr))) {
return 1;
}
int freed = _PyMem_IsFreed(&op->ob_type, sizeof(op->ob_type)); int freed = _PyMem_IsFreed(&op->ob_type, sizeof(op->ob_type));
/* ignore op->ob_ref: the value can have be modified /* ignore op->ob_ref: the value can have be modified
by Py_INCREF() and Py_DECREF(). */ by Py_INCREF() and Py_DECREF(). */
@ -448,6 +452,7 @@ _PyObject_Dump(PyObject* op)
/* It seems like the object memory has been freed: /* It seems like the object memory has been freed:
don't access it to prevent a segmentation fault. */ don't access it to prevent a segmentation fault. */
fprintf(stderr, "<freed object>\n"); fprintf(stderr, "<freed object>\n");
return;
} }
PyGILState_STATE gil; PyGILState_STATE gil;