144 lines
5.5 KiB
Diff
144 lines
5.5 KiB
Diff
From c563f409ea30bcb0623d785428c9257917371b76 Mon Sep 17 00:00:00 2001
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From: "Miss Islington (bot)"
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<31488909+miss-islington@users.noreply.github.com>
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Date: Thu, 23 Jan 2020 06:49:19 -0800
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Subject: [PATCH] bpo-39421: Fix posible crash in heapq with custom comparison
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operators (GH-18118) (GH-18146)
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(cherry picked from commit 79f89e6e5a659846d1068e8b1bd8e491ccdef861)
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Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
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---
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Lib/test/test_heapq.py | 31 ++++++++++++++++
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.../2020-01-22-15-53-37.bpo-39421.O3nG7u.rst | 2 ++
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Modules/_heapqmodule.c | 35 ++++++++++++++-----
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3 files changed, 59 insertions(+), 9 deletions(-)
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create mode 100644 Misc/NEWS.d/next/Core and Builtins/2020-01-22-15-53-37.bpo-39421.O3nG7u.rst
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diff --git a/Lib/test/test_heapq.py b/Lib/test/test_heapq.py
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index 2f8c648d84a58..7c3fb0210f69b 100644
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--- a/Lib/test/test_heapq.py
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+++ b/Lib/test/test_heapq.py
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@@ -414,6 +414,37 @@ def test_heappop_mutating_heap(self):
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with self.assertRaises((IndexError, RuntimeError)):
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self.module.heappop(heap)
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+ def test_comparison_operator_modifiying_heap(self):
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+ # See bpo-39421: Strong references need to be taken
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+ # when comparing objects as they can alter the heap
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+ class EvilClass(int):
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+ def __lt__(self, o):
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+ heap.clear()
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+ return NotImplemented
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+
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+ heap = []
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+ self.module.heappush(heap, EvilClass(0))
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+ self.assertRaises(IndexError, self.module.heappushpop, heap, 1)
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+
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+ def test_comparison_operator_modifiying_heap_two_heaps(self):
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+
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+ class h(int):
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+ def __lt__(self, o):
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+ list2.clear()
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+ return NotImplemented
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+
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+ class g(int):
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+ def __lt__(self, o):
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+ list1.clear()
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+ return NotImplemented
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+
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+ list1, list2 = [], []
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+
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+ self.module.heappush(list1, h(0))
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+ self.module.heappush(list2, g(0))
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+
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+ self.assertRaises((IndexError, RuntimeError), self.module.heappush, list1, g(1))
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+ self.assertRaises((IndexError, RuntimeError), self.module.heappush, list2, h(1))
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class TestErrorHandlingPython(TestErrorHandling, TestCase):
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module = py_heapq
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diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-01-22-15-53-37.bpo-39421.O3nG7u.rst b/Misc/NEWS.d/next/Core and Builtins/2020-01-22-15-53-37.bpo-39421.O3nG7u.rst
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new file mode 100644
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index 0000000000000..bae008150ee12
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--- /dev/null
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+++ b/Misc/NEWS.d/next/Core and Builtins/2020-01-22-15-53-37.bpo-39421.O3nG7u.rst
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@@ -0,0 +1,2 @@
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+Fix possible crashes when operating with the functions in the :mod:`heapq`
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+module and custom comparison operators.
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diff --git a/Modules/_heapqmodule.c b/Modules/_heapqmodule.c
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index b499e1f668aae..0fb35ffe5ec48 100644
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--- a/Modules/_heapqmodule.c
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+++ b/Modules/_heapqmodule.c
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@@ -29,7 +29,11 @@ siftdown(PyListObject *heap, Py_ssize_t startpos, Py_ssize_t pos)
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while (pos > startpos) {
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parentpos = (pos - 1) >> 1;
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parent = arr[parentpos];
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+ Py_INCREF(newitem);
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+ Py_INCREF(parent);
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cmp = PyObject_RichCompareBool(newitem, parent, Py_LT);
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+ Py_DECREF(parent);
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+ Py_DECREF(newitem);
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if (cmp < 0)
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return -1;
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if (size != PyList_GET_SIZE(heap)) {
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@@ -71,10 +75,13 @@ siftup(PyListObject *heap, Py_ssize_t pos)
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/* Set childpos to index of smaller child. */
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childpos = 2*pos + 1; /* leftmost child position */
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if (childpos + 1 < endpos) {
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- cmp = PyObject_RichCompareBool(
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- arr[childpos],
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- arr[childpos + 1],
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- Py_LT);
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+ PyObject* a = arr[childpos];
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+ PyObject* b = arr[childpos + 1];
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+ Py_INCREF(a);
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+ Py_INCREF(b);
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+ cmp = PyObject_RichCompareBool(a, b, Py_LT);
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+ Py_DECREF(a);
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+ Py_DECREF(b);
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if (cmp < 0)
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return -1;
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childpos += ((unsigned)cmp ^ 1); /* increment when cmp==0 */
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@@ -229,7 +236,10 @@ heappushpop(PyObject *self, PyObject *args)
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return item;
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}
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- cmp = PyObject_RichCompareBool(PyList_GET_ITEM(heap, 0), item, Py_LT);
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+ PyObject* top = PyList_GET_ITEM(heap, 0);
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+ Py_INCREF(top);
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+ cmp = PyObject_RichCompareBool(top, item, Py_LT);
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+ Py_DECREF(top);
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if (cmp < 0)
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return NULL;
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if (cmp == 0) {
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@@ -383,7 +393,11 @@ siftdown_max(PyListObject *heap, Py_ssize_t startpos, Py_ssize_t pos)
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while (pos > startpos) {
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parentpos = (pos - 1) >> 1;
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parent = arr[parentpos];
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+ Py_INCREF(parent);
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+ Py_INCREF(newitem);
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cmp = PyObject_RichCompareBool(parent, newitem, Py_LT);
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+ Py_DECREF(parent);
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+ Py_DECREF(newitem);
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if (cmp < 0)
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return -1;
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if (size != PyList_GET_SIZE(heap)) {
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@@ -425,10 +439,13 @@ siftup_max(PyListObject *heap, Py_ssize_t pos)
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/* Set childpos to index of smaller child. */
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childpos = 2*pos + 1; /* leftmost child position */
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if (childpos + 1 < endpos) {
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- cmp = PyObject_RichCompareBool(
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- arr[childpos + 1],
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- arr[childpos],
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- Py_LT);
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+ PyObject* a = arr[childpos + 1];
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+ PyObject* b = arr[childpos];
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+ Py_INCREF(a);
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+ Py_INCREF(b);
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+ cmp = PyObject_RichCompareBool(a, b, Py_LT);
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+ Py_DECREF(a);
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+ Py_DECREF(b);
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if (cmp < 0)
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return -1;
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childpos += ((unsigned)cmp ^ 1); /* increment when cmp==0 */
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