bpo-36791: Safer detection of integer overflow in sum(). (GH-13080)

29500737 · Serhiy Storchaka · GitHub · 88f07a80 · 29500737
Unverified Kaydet (Commit) 29500737 authored May 05, 2019 tarafından Serhiy Storchaka Kaydeden (comit) GitHub May 05, 2019
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bltinmodule.c Python/bltinmodule.c +5 -3

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--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -2375,9 +2375,11 @@ builtin_sum_impl(PyObject *module, PyObject *iterable, PyObject *start)
            }
            if (PyLong_CheckExact(item)) {
                long b = PyLong_AsLongAndOverflow(item, &overflow);
-                long x = i_result + b;
+                if (overflow == 0 &&
-                if (overflow == 0 && ((x^i_result) >= 0 || (x^b) >= 0)) {
+                    (i_result >= 0 ? (b <= LONG_MAX - i_result)
-                    i_result = x;
+                                   : (b >= LONG_MIN - i_result)))
+                {
+                    i_result += b;
                    Py_DECREF(item);
                    continue;
                }