linux-kernel - [PATCH v3 2/2] rust: uaccess: refactor to use `overflow

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Message-ID: <20250621230231.100181-3-contact@antoniohickey.com>
Date: Sat, 21 Jun 2025 23:03:27 +0000
From: Antonio Hickey <contact@...oniohickey.com>
To: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>, Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, Björn Roy Baron <bjorn3_gh@...tonmail.com>, Benno Lossin <lossin@...nel.org>, Andreas Hindborg <a.hindborg@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>
Cc: Antonio Hickey <contact@...oniohickey.com>, Daniel Cote <danielstonecote@...il.com>, rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 2/2] rust: uaccess: refactor to use `overflow_assert!`

Using the `overflow_assert!` macro here adds documentation to
the intent of the assertion, and avoids local `#ifdefs`s by
encapsulating the conditional behavior to the macro itself.

Co-developed-by: Daniel Cote <danielstonecote@...il.com>
Signed-off-by: Daniel Cote <danielstonecote@...il.com>
Signed-off-by: Antonio Hickey <contact@...oniohickey.com>
Link: https://github.com/Rust-for-Linux/linux/issues/1159
Suggested-by: Miguel Ojeda <ojeda@...nel.org>
---
 rust/kernel/uaccess.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/rust/kernel/uaccess.rs b/rust/kernel/uaccess.rs
index 635a03e0989f..452a5e0d76d2 100644
--- a/rust/kernel/uaccess.rs
+++ b/rust/kernel/uaccess.rs
@@ -9,6 +9,7 @@
     bindings,
     error::Result,
     ffi::{c_char, c_void},
+    overflow_assert,
     prelude::*,
     transmute::{AsBytes, FromBytes},
 };
@@ -394,8 +395,7 @@ fn raw_strncpy_from_user(dst: &mut [MaybeUninit<u8>], src: UserPtr) -> Result<us
         return Err(Error::from_errno(res as i32));
     }
 
-    #[cfg(CONFIG_RUST_OVERFLOW_CHECKS)]
-    assert!(res <= len);
+    overflow_assert!(res <= len);
 
     // GUARANTEES: `strncpy_from_user` was successful, so `dst` has contents in accordance with the
     // guarantees of this function.
-- 
2.50.0