8000 bpo-9263: Fix _PyObject_Dump() for freed object by vstinner · Pull Request #10661 · python/cpython · GitHub
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bpo-9263: Fix _PyObject_Dump() for freed object #10661

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merged 1 commit into from
Nov 22, 2018
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bpo-9263: Fix _PyObject_Dump() for freed object #10661

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bpo-9263: Fix _PyObject_Dump() for freed object 
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.
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@vstinner
vstinner committed Nov 22, 2018
commit d5961d9e877726050978a3ff06d0bb65d0ef3945
5 changes: 5 additions & 0 deletions Objects/object.c
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Original file line number Diff line number Diff line change
Expand Up @@ -423,6 +423,10 @@ _Py_BreakPoint(void)
int
_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));
/* ignore op->ob_ref: the value can have be modified
by Py_INCREF() and Py_DECREF(). */
Expand All @@ -448,6 +452,7 @@ _PyObject_Dump(PyObject* op)
/* It seems like the object memory has been freed:
don't access it to prevent a segmentation fault. */
fprintf(stderr, "<freed object>\n");
return;
}

PyGILState_STATE gil;
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