[Python-checkins] bpo-35961: Fix a crash in slice_richcompare() (GH-11830)
Victor Stinner
webhook-mailer at python.org
Wed Feb 13 06:32:02 EST 2019
https://github.com/python/cpython/commit/dcb68f47f74b0cc8a1896d4a4c5a6b83c0bbeeae
commit: dcb68f47f74b0cc8a1896d4a4c5a6b83c0bbeeae
branch: master
author: Victor Stinner <vstinner at redhat.com>
committer: GitHub <noreply at github.com>
date: 2019-02-13T12:31:56+01:00
summary:
bpo-35961: Fix a crash in slice_richcompare() (GH-11830)
Fix a crash in slice_richcompare(): use strong references rather than
stolen references for the two temporary internal tuples.
The crash (or assertion error) occurred if a garbage collection
occurred during slice_richcompare(), especially while calling
PyObject_RichCompare(t1, t2, op).
files:
A Misc/NEWS.d/next/Core and Builtins/2019-02-12-20-16-34.bpo-35961.7f7Sne.rst
M Objects/sliceobject.c
diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-02-12-20-16-34.bpo-35961.7f7Sne.rst b/Misc/NEWS.d/next/Core and Builtins/2019-02-12-20-16-34.bpo-35961.7f7Sne.rst
new file mode 100644
index 000000000000..943aaa2f3c80
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2019-02-12-20-16-34.bpo-35961.7f7Sne.rst
@@ -0,0 +1,2 @@
+Fix a crash in slice_richcompare(): use strong references rather than stolen
+references for the two temporary internal tuples.
diff --git a/Objects/sliceobject.c b/Objects/sliceobject.c
index c60483ea9494..2dcb44fdee57 100644
--- a/Objects/sliceobject.c
+++ b/Objects/sliceobject.c
@@ -565,14 +565,11 @@ static PyMethodDef slice_methods[] = {
static PyObject *
slice_richcompare(PyObject *v, PyObject *w, int op)
{
- PyObject *t1;
- PyObject *t2;
- PyObject *res;
-
if (!PySlice_Check(v) || !PySlice_Check(w))
Py_RETURN_NOTIMPLEMENTED;
if (v == w) {
+ PyObject *res;
/* XXX Do we really need this shortcut?
There's a unit test for it, but is that fair? */
switch (op) {
@@ -589,34 +586,27 @@ slice_richcompare(PyObject *v, PyObject *w, int op)
return res;
}
- t1 = PyTuple_New(3);
- if (t1 == NULL)
+
+ PyObject *t1 = PyTuple_Pack(3,
+ ((PySliceObject *)v)->start,
+ ((PySliceObject *)v)->stop,
+ ((PySliceObject *)v)->step);
+ if (t1 == NULL) {
return NULL;
- t2 = PyTuple_New(3);
+ }
+
+ PyObject *t2 = PyTuple_Pack(3,
+ ((PySliceObject *)w)->start,
+ ((PySliceObject *)w)->stop,
+ ((PySliceObject *)w)->step);
if (t2 == NULL) {
Py_DECREF(t1);
return NULL;
}
- PyTuple_SET_ITEM(t1, 0, ((PySliceObject *)v)->start);
- PyTuple_SET_ITEM(t1, 1, ((PySliceObject *)v)->stop);
- PyTuple_SET_ITEM(t1, 2, ((PySliceObject *)v)->step);
- PyTuple_SET_ITEM(t2, 0, ((PySliceObject *)w)->start);
- PyTuple_SET_ITEM(t2, 1, ((PySliceObject *)w)->stop);
- PyTuple_SET_ITEM(t2, 2, ((PySliceObject *)w)->step);
-
- res = PyObject_RichCompare(t1, t2, op);
-
- PyTuple_SET_ITEM(t1, 0, NULL);
- PyTuple_SET_ITEM(t1, 1, NULL);
- PyTuple_SET_ITEM(t1, 2, NULL);
- PyTuple_SET_ITEM(t2, 0, NULL);
- PyTuple_SET_ITEM(t2, 1, NULL);
- PyTuple_SET_ITEM(t2, 2, NULL);
-
+ PyObject *res = PyObject_RichCompare(t1, t2, op);
Py_DECREF(t1);
Py_DECREF(t2);
-
return res;
}
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