Issue 13496: Fix bisect.bisect overflow bug for large collections.
diff --git a/Modules/_bisectmodule.c b/Modules/_bisectmodule.c
index e8976b2..4798c12 100644
--- a/Modules/_bisectmodule.c
+++ b/Modules/_bisectmodule.c
@@ -21,7 +21,13 @@
return -1;
}
while (lo < hi) {
- mid = (lo + hi) / 2;
+ /* The (size_t)cast ensures that the addition and subsequent division
+ are performed as unsigned operations, avoiding difficulties from
+ signed overflow. (See issue 13496.) */
+ printf("lo: %d\n", lo);
+ printf("hi: %d\n", hi);
+ printf("mid: %d\n", mid);
+ mid = ((size_t)lo + hi) / 2;
litem = PySequence_GetItem(list, mid);
if (litem == NULL)
return -1;
@@ -122,7 +128,10 @@
return -1;
}
while (lo < hi) {
- mid = (lo + hi) / 2;
+ /* The (size_t)cast ensures that the addition and subsequent division
+ are performed as unsigned operations, avoiding difficulties from
+ signed overflow. (See issue 13496.) */
+ mid = ((size_t)lo + hi) / 2;
litem = PySequence_GetItem(list, mid);
if (litem == NULL)
return -1;