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Merged revisions 76629 via svnmerge from 

svn+ssh://pythondev@svn.python.org/python/trunk

........
  r76629 | mark.dickinson | 2009-12-02 17:33:41 +0000 (Wed, 02 Dec 2009) | 3 lines

  Issue #7406:  Fix some occurrences of potential signed overflow in int
  arithmetic.
........
This commit is contained in:
Mark Dickinson 2009-12-02 17:36:34 +00:00
parent 0d124c29e2
commit 6df863c93a
2 changed files with 12 additions and 5 deletions
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9
Objects/intobject.c
View File

@ -465,7 +465,8 @@ int_add(PyIntObject *v, PyIntObject *w)
register long a, b, x;
CONVERT_TO_LONG(v, a);
CONVERT_TO_LONG(w, b);
x = a + b;
/* casts in the line below avoid undefined behaviour on overflow */
x = (long)((unsigned long)a + b);
if ((x^a) >= 0 || (x^b) >= 0)
return PyInt_FromLong(x);
return PyLong_Type.tp_as_number->nb_add((PyObject *)v, (PyObject *)w);
@ -477,7 +478,8 @@ int_sub(PyIntObject *v, PyIntObject *w)
register long a, b, x;
CONVERT_TO_LONG(v, a);
CONVERT_TO_LONG(w, b);
x = a - b;
/* casts in the line below avoid undefined behaviour on overflow */
x = (long)((unsigned long)a - b);
if ((x^a) >= 0 || (x^~b) >= 0)
return PyInt_FromLong(x);
return PyLong_Type.tp_as_number->nb_subtract((PyObject *)v,
@ -520,7 +522,8 @@ int_mul(PyObject *v, PyObject *w)
CONVERT_TO_LONG(v, a);
CONVERT_TO_LONG(w, b);
longprod = a * b;
/* casts in the next line avoid undefined behaviour on overflow */
longprod = (long)((unsigned long)a * b);
doubleprod = (double)a * (double)b;
doubled_longprod = (double)longprod;

8
Python/ceval.c
View File

@ -1191,7 +1191,9 @@ 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);
@ -1221,7 +1223,9 @@ 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);