Issue #1621: Avoid signed overflow in list and tuple operations
Patch by Xiang Zhang.
diff --git a/Objects/listobject.c b/Objects/listobject.c
index ddc0fee..0b2c8c1 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -488,9 +488,9 @@
return NULL;
}
#define b ((PyListObject *)bb)
- size = Py_SIZE(a) + Py_SIZE(b);
- if (size < 0)
+ if (Py_SIZE(a) > PY_SSIZE_T_MAX - Py_SIZE(b))
return PyErr_NoMemory();
+ size = Py_SIZE(a) + Py_SIZE(b);
np = (PyListObject *) PyList_New(size);
if (np == NULL) {
return NULL;
@@ -841,18 +841,20 @@
return NULL;
}
m = Py_SIZE(self);
- mn = m + n;
- if (mn >= m) {
+ if (m > PY_SSIZE_T_MAX - n) {
+ /* m + n overflowed; on the chance that n lied, and there really
+ * is enough room, ignore it. If n was telling the truth, we'll
+ * eventually run out of memory during the loop.
+ */
+ }
+ else {
+ mn = m + n;
/* Make room. */
if (list_resize(self, mn) < 0)
goto error;
/* Make the list sane again. */
Py_SIZE(self) = m;
}
- /* Else m + n overflowed; on the chance that n lied, and there really
- * is enough room, ignore it. If n was telling the truth, we'll
- * eventually run out of memory during the loop.
- */
/* Run iterator to exhaustion. */
for (;;) {
diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
index 1b41258..c0ff499 100644
--- a/Objects/tupleobject.c
+++ b/Objects/tupleobject.c
@@ -453,9 +453,9 @@
return NULL;
}
#define b ((PyTupleObject *)bb)
- size = Py_SIZE(a) + Py_SIZE(b);
- if (size < 0)
+ if (Py_SIZE(a) > PY_SSIZE_T_MAX - Py_SIZE(b))
return PyErr_NoMemory();
+ size = Py_SIZE(a) + Py_SIZE(b);
np = (PyTupleObject *) PyTuple_New(size);
if (np == NULL) {
return NULL;