bpo-1621: Avoid signed integer overflow in set_table_resize(). (GH-9059)
Address a C undefined behavior signed integer overflow issue in set object table resizing. Our -fwrapv compiler flag and practical reasons why sets are unlikely to get this large should mean this was never an issue but it was incorrect code that generates code analysis warnings.
<!-- issue-number: [bpo-1621](https://www.bugs.python.org/issue1621) -->
https://bugs.python.org/issue1621
<!-- /issue-number -->
diff --git a/Objects/setobject.c b/Objects/setobject.c
index 82b5838..e7a5288 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -302,7 +302,6 @@
static int
set_table_resize(PySetObject *so, Py_ssize_t minused)
{
- Py_ssize_t newsize;
setentry *oldtable, *newtable, *entry;
Py_ssize_t oldmask = so->mask;
size_t newmask;
@@ -313,13 +312,9 @@
/* Find the smallest table size > minused. */
/* XXX speed-up with intrinsics */
- for (newsize = PySet_MINSIZE;
- newsize <= minused && newsize > 0;
- newsize <<= 1)
- ;
- if (newsize <= 0) {
- PyErr_NoMemory();
- return -1;
+ size_t newsize = PySet_MINSIZE;
+ while (newsize <= (size_t)minused) {
+ newsize <<= 1; // The largest possible value is PY_SSIZE_T_MAX + 1.
}
/* Get space for a new table. */