linux-kernel - [PATCH 1/2] rust: lockdep: Remove support for dynamically allocated LockClassKeys

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Message-Id: <20241004-rust-lockdep-v1-1-e9a5c45721fc@gmail.com>
Date: Fri, 04 Oct 2024 15:01:37 -0700
From: Mitchell Levy via B4 Relay <devnull+levymitchell0.gmail.com@...nel.org>
To: Boqun Feng <boqun.feng@...il.com>, Miguel Ojeda <ojeda@...nel.org>, 
 Alex Gaynor <alex.gaynor@...il.com>, 
 Wedson Almeida Filho <wedsonaf@...il.com>, Gary Guo <gary@...yguo.net>, 
 Björn Roy Baron <bjorn3_gh@...tonmail.com>, 
 Benno Lossin <benno.lossin@...ton.me>, Alice Ryhl <aliceryhl@...gle.com>, 
 Trevor Gross <tmgross@...ch.edu>, Andreas Hindborg <a.hindborg@...nel.org>, 
 Andreas Hindborg <a.hindborg@...nel.org>
Cc: linux-block@...r.kernel.org, rust-for-linux@...r.kernel.org, 
 linux-kernel@...r.kernel.org, stable@...r.kernel.org, 
 Mitchell Levy <levymitchell0@...il.com>
Subject: [PATCH 1/2] rust: lockdep: Remove support for dynamically
 allocated LockClassKeys

From: Mitchell Levy <levymitchell0@...il.com>

Currently, dynamically allocated LockCLassKeys can be used from the Rust
side without having them registered. This is a soundness issue, so
remove them.

Suggested-by: Alice Ryhl <aliceryhl@...gle.com>
Link: https://lore.kernel.org/rust-for-linux/20240815074519.2684107-3-nmi@metaspace.dk/
Cc: stable@...r.kernel.org
Signed-off-by: Mitchell Levy <levymitchell0@...il.com>
---
 rust/kernel/lib.rs  |  2 +-
 rust/kernel/sync.rs | 14 ++------------
 2 files changed, 3 insertions(+), 13 deletions(-)

diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 22a3bfa5a9e9..b5f4b3ce6b48 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -44,8 +44,8 @@
 pub mod page;
 pub mod prelude;
 pub mod print;
-pub mod sizes;
 pub mod rbtree;
+pub mod sizes;
 mod static_assert;
 #[doc(hidden)]
 pub mod std_vendor;
diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs
index 0ab20975a3b5..d270db9b9894 100644
--- a/rust/kernel/sync.rs
+++ b/rust/kernel/sync.rs
@@ -27,28 +27,18 @@
 unsafe impl Sync for LockClassKey {}
 
 impl LockClassKey {
-    /// Creates a new lock class key.
-    pub const fn new() -> Self {
-        Self(Opaque::uninit())
-    }
-
     pub(crate) fn as_ptr(&self) -> *mut bindings::lock_class_key {
         self.0.get()
     }
 }
 
-impl Default for LockClassKey {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-
 /// Defines a new static lock class and returns a pointer to it.
 #[doc(hidden)]
 #[macro_export]
 macro_rules! static_lock_class {
     () => {{
-        static CLASS: $crate::sync::LockClassKey = $crate::sync::LockClassKey::new();
+        static CLASS: $crate::sync::LockClassKey =
+            unsafe { ::core::mem::MaybeUninit::uninit().assume_init() };
         &CLASS
     }};
 }

-- 
2.34.1