From fd82f16c1e4d9a0661e9a2250004032797652e69 Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
<31488909+miss-islington@users.noreply.github.com>
Date: Wed, 5 Oct 2022 14:55:53 -0700
Subject: [PATCH] [3.7] gh-97616: list_resize() checks for integer overflow
(GH-97617) (#97629)
Fix multiplying a list by an integer (list *= int): detect the
integer overflow when the new allocated length is close to the
maximum size. Issue reported by Jordan Limor.
list_resize() now checks for integer overflow before multiplying the
new allocated length by the list item size (sizeof(PyObject*)).
(cherry picked from commit a5f092f3c469b674b8d9ccbd4e4377230c9ac7cf)
Co-authored-by: Victor Stinner <vstinner@python.org>
---
Lib/test/test_list.py | 13 +++++++++++++
.../2022-09-28-17-09-37.gh-issue-97616.K1e3Xs.rst | 3 +++
Objects/listobject.c | 10 ++++++++--
3 files changed, 24 insertions(+), 2 deletions(-)
create mode 100644 Misc/NEWS.d/next/Security/2022-09-28-17-09-37.gh-issue-97616.K1e3Xs.rst
diff --git a/Lib/test/test_list.py b/Lib/test/test_list.py
index 32bf17564c9..c9cdc1e384a 100644
--- a/Lib/test/test_list.py
+++ b/Lib/test/test_list.py
@@ -67,6 +67,19 @@ def imul(a, b): a *= b
self.assertRaises((MemoryError, OverflowError), mul, lst, n)
self.assertRaises((MemoryError, OverflowError), imul, lst, n)
+ def test_list_resize_overflow(self):
+ # gh-97616: test new_allocated * sizeof(PyObject*) overflow
+ # check in list_resize()
+ lst = [0] * 65
+ del lst[1:]
+ self.assertEqual(len(lst), 1)
+
+ size = ((2 ** (tuple.__itemsize__ * 8) - 1) // 2)
+ with self.assertRaises((MemoryError, OverflowError)):
+ lst * size
+ with self.assertRaises((MemoryError, OverflowError)):
+ lst *= size
+
def test_repr_large(self):
# Check the repr of large list objects
def check(n):
diff --git a/Misc/NEWS.d/next/Security/2022-09-28-17-09-37.gh-issue-97616.K1e3Xs.rst b/Misc/NEWS.d/next/Security/2022-09-28-17-09-37.gh-issue-97616.K1e3Xs.rst
new file mode 100644
index 00000000000..721427fe646
--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2022-09-28-17-09-37.gh-issue-97616.K1e3Xs.rst
@@ -0,0 +1,3 @@
+Fix multiplying a list by an integer (``list *= int``): detect the integer
+overflow when the new allocated length is close to the maximum size. Issue
+reported by Jordan Limor. Patch by Victor Stinner.
diff --git a/Objects/listobject.c b/Objects/listobject.c
index 158ca11d032..60837fcf1e1 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -64,8 +64,14 @@ list_resize(PyListObject *self, Py_ssize_t newsize)
if (newsize == 0)
new_allocated = 0;
- num_allocated_bytes = new_allocated * sizeof(PyObject *);
- items = (PyObject **)PyMem_Realloc(self->ob_item, num_allocated_bytes);
+ if (new_allocated <= (size_t)PY_SSIZE_T_MAX / sizeof(PyObject *)) {
+ num_allocated_bytes = new_allocated * sizeof(PyObject *);
+ items = (PyObject **)PyMem_Realloc(self->ob_item, num_allocated_bytes);
+ }
+ else {
+ // integer overflow
+ items = NULL;
+ }
if (items == NULL) {
PyErr_NoMemory();
return -1;
--
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