rust: allow `suspicious_runtime_symbol_definitions` lint for Rust >= 1.98

Starting with Rust 1.98.0 (expected 2026-08-20), Rust is introducing a
couple new lints, `invalid_runtime_symbol_definitions` (deny-by-default)
and `suspicious_runtime_symbol_definitions` (warn-by-default), which check
the signature of items whose symbol name is a runtime symbol expected by
`core`.

Our build hits the second one, i.e. the warning:

    error: suspicious definition of the runtime `strlen` symbol used by the standard library
         --> rust/bindings/bindings_generated.rs:20018:5
          |
    20018 |     pub fn strlen(s: *const ffi::c_char) -> usize;
          |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
          |
          = note: expected `unsafe extern "C" fn(*const i8) -> usize`
                  found    `unsafe extern "C" fn(*const u8) -> usize`
          = help: either fix the signature or remove any attributes like `#[unsafe(no_mangle)]`, `#[unsafe(export_name = "strlen")]`, or `#[link_name = "strlen"]`
          = help: allow this lint if the signature is compatible
          = note: `-D suspicious-runtime-symbol-definitions` implied by `-D warnings`
          = help: to override `-D warnings` add `#[allow(suspicious_runtime_symbol_definitions)]`

    error: suspicious definition of the runtime `strlen` symbol used by the standard library
         --> rust/uapi/uapi_generated.rs:14236:5
          |
    14236 |     pub fn strlen(s: *const ffi::c_char) -> usize;
          |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
          |
          = note: expected `unsafe extern "C" fn(*const i8) -> usize`
                  found    `unsafe extern "C" fn(*const u8) -> usize`
          = help: either fix the signature or remove any attributes like `#[unsafe(no_mangle)]`, `#[unsafe(export_name = "strlen")]`, or `#[link_name = "strlen"]`
          = help: allow this lint if the signature is compatible
          = note: `-D suspicious-runtime-symbol-definitions` implied by `-D warnings`
          = help: to override `-D warnings` add `#[allow(suspicious_runtime_symbol_definitions)]`

Thus `allow` the lint in `bindings` and `uapi`.

A more targeted alternative to avoid `allow`ing it would be to pass
`--blocklist-function strlen` to `bindgen`, but we would perhaps need
to adjust if other C headers end up adding more (or Rust checking more).
Since it is just the less critical one that we hit, and since eventually
this should be properly fixed by getting upstream Rust to provide a flag
like GCC/Clang's `-funsigned-char` [2][3], just `allow` it for now.

Cc: Urgau <urgau@numericable.fr>
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: https://github.com/rust-lang/rust/pull/155521
Link: https://github.com/rust-lang/rust/issues/138446
Link: https://github.com/Rust-for-Linux/linux/issues/355
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Tamir Duberstein <tamird@kernel.org>
Link: https://patch.msgid.link/20260615143225.471756-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

diff --git a/init/Kconfig b/init/Kconfig
index 5230d4879b1c84b1d6d735adc9f7ee270b27635f..10f2013b532169f84b4f904ae93fd32831903a8e 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -190,6 +190,9 @@ config RUSTC_HAS_FILE_WITH_NUL
 config RUSTC_HAS_FILE_AS_C_STR
        def_bool RUSTC_VERSION >= 109100
 
+config RUSTC_HAS_SUSPICIOUS_RUNTIME_SYMBOL_DEFINITIONS
+       def_bool RUSTC_VERSION >= 109800
+
 config PAHOLE_VERSION
        int
        default "$(PAHOLE_VERSION)"

diff --git a/rust/bindings/lib.rs b/rust/bindings/lib.rs
index 854e7c471434c6270185e2b95b2da5959dc15cf0..812f8e5a08d536ed6e0a89911d48ae4874b91314 100644 (file)
--- a/rust/bindings/lib.rs
+++ b/rust/bindings/lib.rs
@@ -27,6 +27,10 @@
 #[allow(clippy::ref_as_ptr)]
 #[allow(clippy::undocumented_unsafe_blocks)]
 #[cfg_attr(CONFIG_RUSTC_HAS_UNNECESSARY_TRANSMUTES, allow(unnecessary_transmutes))]
+#[cfg_attr(
+    CONFIG_RUSTC_HAS_SUSPICIOUS_RUNTIME_SYMBOL_DEFINITIONS,
+    allow(suspicious_runtime_symbol_definitions)
+)]
 mod bindings_raw {
     use pin_init::{MaybeZeroable, Zeroable};
 

diff --git a/rust/uapi/lib.rs b/rust/uapi/lib.rs
index b8a515de31cae7774f3490aa7e3e440978045e53..797ead5b5626ce5e6a4ab47aa396cdfd91df83ef 100644 (file)
--- a/rust/uapi/lib.rs
+++ b/rust/uapi/lib.rs
@@ -24,6 +24,10 @@
     unsafe_op_in_unsafe_fn
 )]
 #![cfg_attr(CONFIG_RUSTC_HAS_UNNECESSARY_TRANSMUTES, allow(unnecessary_transmutes))]
+#![cfg_attr(
+    CONFIG_RUSTC_HAS_SUSPICIOUS_RUNTIME_SYMBOL_DEFINITIONS,
+    allow(suspicious_runtime_symbol_definitions)
+)]
 #![feature(cfi_encoding)]
 
 // Manual definition of blocklisted types.