From 1fb20dab91068b44fa0b0bda79052de00d2c6980 Mon Sep 17 00:00:00 2001
From: Amanieu d'Antras <amanieu@gmail.com>
Date: Mon, 20 Dec 2021 18:28:36 +0100
Subject: [PATCH 1/2] Avoid UB in PySlice::indices

Mutating a variables that is not declared with `mut` is undefined
behavior.
---
 src/types/slice.rs | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/types/slice.rs b/src/types/slice.rs
index 6187e26a..90cd09da 100644
--- a/src/types/slice.rs
+++ b/src/types/slice.rs
@@ -57,17 +57,17 @@ impl PySlice {
     pub fn indices(&self, length: c_long) -> PyResult<PySliceIndices> {
         // non-negative Py_ssize_t should always fit into Rust usize
         unsafe {
-            let slicelength: isize = 0;
-            let start: isize = 0;
-            let stop: isize = 0;
-            let step: isize = 0;
+            let mut slicelength: isize = 0;
+            let mut start: isize = 0;
+            let mut stop: isize = 0;
+            let mut step: isize = 0;
             let r = ffi::PySlice_GetIndicesEx(
                 self.as_ptr(),
                 length as Py_ssize_t,
-                &start as *const _ as *mut _,
-                &stop as *const _ as *mut _,
-                &step as *const _ as *mut _,
-                &slicelength as *const _ as *mut _,
+                &mut start,
+                &mut stop,
+                &mut step,
+                &mut slicelength,
             );
             if r == 0 {
                 Ok(PySliceIndices {

From ed0a6b710ae731ad9c9ae6567d278c0624b0ddff Mon Sep 17 00:00:00 2001
From: Amanieu d'Antras <amanieu@gmail.com>
Date: Mon, 20 Dec 2021 18:34:14 +0100
Subject: [PATCH 2/2] Add changelog entry

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c15ec83f..c39cdb45 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -49,6 +49,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fix undefined symbol for `PyObject_HasAttr` on PyPy. [#2025](https://github.com/PyO3/pyo3/pull/2025)
 - Fix memory leak in `PyErr::into_value`. [#2026](https://github.com/PyO3/pyo3/pull/2026)
 - Fix clippy warning `needless-option-as-deref` in code generated by `#[pyfunction]` and `#[pymethods]`. [#2040](https://github.com/PyO3/pyo3/pull/2040)
+- Fix undefined behavior in `PySlice::indices`. [#2061](https://github.com/PyO3/pyo3/pull/2061)
 
 ## [0.15.1] - 2021-11-19