Issue #24913: Fix overrun error in deque.index().

brettcannon · brettcannon · commit df6b544ff6f3 · 2015-09-03T10:15:03.000-07:00
Reported by John Leitch and Bryce Darling, patch by Raymond Hettinger.
diff --git a/Lib/test/test_deque.py b/Lib/test/test_deque.py
@@ -289,6 +289,11 @@ def test_index(self):
                     else:
                         self.assertEqual(d.index(element, start, stop), target)
 
+    def test_insert_bug_24913(self):
+        d = deque('A' * 3)
+        with self.assertRaises(ValueError):
+            i = d.index("Hello world", 0, 4)
+
     def test_insert(self):
         # Test to make sure insert behaves like lists
         elements = 'ABCDEFGHI'
diff --git a/Misc/NEWS b/Misc/NEWS
@@ -15,6 +15,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #24913: Fix overrun error in deque.index().
+  Found by John Leitch and Bryce Darling.
+
 
 What's New in Python 3.5.0 release candidate 2?
 ===============================================
diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
@@ -924,6 +924,8 @@ deque_index(dequeobject *deque, PyObject *args)
         if (stop < 0)
             stop = 0;
     }
+    if (stop > Py_SIZE(deque))
+        stop = Py_SIZE(deque);
 
     for (i=0 ; i<stop ; i++) {
         if (i >= start) {

Original file line number	Diff line number	Diff line change
`@@ -924,6 +924,8 @@ deque_index(dequeobject deque, PyObject args)`
`924`	`924`	`if (stop < 0)`
`925`	`925`	`stop = 0;`
`926`	`926`	`}`
	`927`	`+ if (stop > Py_SIZE(deque))`
	`928`	`+ stop = Py_SIZE(deque);`
`927`	`929`
`928`	`930`	`for (i=0 ; i<stop ; i++) {`
`929`	`931`	`if (i >= start) {`