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Issue #7406: Fix some occurrences of potential signed overflow in int

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arithmetic.
This commit is contained in:
Mark Dickinson 2009-12-02 17:33:41 +00:00
parent 5a73ff81f1
commit 34398184eb
2 changed files with 12 additions and 5 deletions
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8
Python/ceval.c
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@ -1321,7 +1321,9 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
register long a, b, i;
a = PyInt_AS_LONG(v);
b = PyInt_AS_LONG(w);
i = a + b;
/* cast to avoid undefined behaviour
on overflow */
i = (long)((unsigned long)a + b);
if ((i^a) < 0 && (i^b) < 0)
goto slow_add;
x = PyInt_FromLong(i);
@ -1351,7 +1353,9 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
register long a, b, i;
a = PyInt_AS_LONG(v);
b = PyInt_AS_LONG(w);
i = a - b;
/* cast to avoid undefined behaviour
on overflow */
i = (long)((unsigned long)a - b);
if ((i^a) < 0 && (i^~b) < 0)
goto slow_sub;
x = PyInt_FromLong(i);