gh-125889: Fix bounds check of hi argument in bisect_left|right functions

Lib/test/test_bisect.py

@@ -126,6 +126,20 @@ def test_negative_lo(self):
         self.assertRaises(ValueError, mod.insort_left, [1, 2, 3], 5, -1, 3)
         self.assertRaises(ValueError, mod.insort_right, [1, 2, 3], 5, -1, 3)
 
+    def test_negative_hi(self):
+        # Issue 125889
+        def assertNoRiases(f, *arg, **kwargs):
+            try:
+                f(*arg, **kwargs)
+            except Exception:
+                self.fail('Unable to work negative hi argument')
+        mod = self.module
+        # It can work negative values
+        assertNoRiases(mod.bisect_left, [1, 2, 3], 5, 3, -2)
+        assertNoRiases(mod.bisect_right, [1, 2, 3], 5, 3, -2)
+        assertNoRiases(mod.insort_left, [1, 2, 3], 5, 3, -2)
+        assertNoRiases(mod.insort_right, [1, 2, 3], 5, 3, -2)
+
     def test_large_range(self):
         # Issue 13496
         mod = self.module

Misc/NEWS.d/next/Library/2024-10-24-15-21-03.gh-issue-125889.P9MXpN.rst

@@ -0,0 +1,2 @@
+Modify the check of the ``hi`` argument in ``internal_bisect_left`` and ``internal_bisect_right``
+so that when ``hi`` is negative, it's calculated based on the list length.

Modules/_bisectmodule.c

@@ -61,7 +61,7 @@ internal_bisect_right(PyObject *list, PyObject *item, Py_ssize_t lo, Py_ssize_t
         PyErr_SetString(PyExc_ValueError, "lo must be non-negative");
         return -1;
     }
-    if (hi == -1) {
+    if (hi < 0) {
         hi = PySequence_Size(list);
         if (hi < 0)
             return -1;
@@ -245,7 +245,7 @@ internal_bisect_left(PyObject *list, PyObject *item, Py_ssize_t lo, Py_ssize_t h
         PyErr_SetString(PyExc_ValueError, "lo must be non-negative");
         return -1;
     }
-    if (hi == -1) {
+    if (hi < 0) {
         hi = PySequence_Size(list);
         if (hi < 0)
             return -1;