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.
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diff --git a/Python/ceval.c b/Python/ceval.c
index abe157e..6c71c27 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -1191,7 +1191,9 @@
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 @@
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);