Boqun Feng a5a3c952e8 rust: macros: provide correct provenance when constructing THIS_MODULE ... Currently while defining `THIS_MODULE` symbol in `module!()`, the pointer used to construct `ThisModule` is derived from an immutable reference of `__this_module`, which means the pointer doesn't have the provenance for writing, and that means any write to that pointer is UB regardless of data races or not. However, the usage of `THIS_MODULE` includes passing this pointer to functions that may write to it (probably in unsafe code), and this will create soundness issues. One way to fix this is using `addr_of_mut!()` but that requires the unstable feature "const_mut_refs". So instead of `addr_of_mut()!`, an extern static `Opaque` is used here: since `Opaque<T>` is transparent to `T`, an extern static `Opaque` will just wrap the C symbol (defined in a C compile unit) in an `Opaque`, which provides a pointer with writable provenance via `Opaque::get()`. This fix the potential UBs because of pointer provenance unmatched. Reported-by: Alice Ryhl <aliceryhl@google.com> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Trevor Gross <tmgross@umich.edu> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Gary Guo <gary@garyguo.net> Closes: https://rust-for-linux.zulipchat.com/#narrow/stream/x/topic/x/near/465412664 Fixes: 1fbde52bde ("rust: add `macros` crate") Cc: stable@vger.kernel.org # 6.6.x: be2ca1e039: ("rust: types: Make Opaque::get const") Link: https://lore.kernel.org/r/20240828180129.4046355-1-boqun.feng@gmail.com [ Fixed two typos, reworded title. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>		2024-09-02 09:14:28 +02:00
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bindings	Rust changes for v6.11	2024-07-27 13:44:54 -07:00
kernel	rust: alloc: eschew Box<MaybeUninit<T>>::write	2024-08-27 00:07:05 +02:00
macros	rust: macros: provide correct provenance when constructing THIS_MODULE	2024-09-02 09:14:28 +02:00
uapi	rust: allow dead_code for never constructed bindings	2024-07-10 10:28:51 +02:00
.gitignore	rust: support running Rust documentation tests as KUnit ones	2023-07-19 09:32:53 -06:00
bindgen_parameters	rust: Ignore preserve-most functions	2023-12-13 01:09:55 +01:00
build_error.rs	rust: add build_error crate	2022-12-04 01:59:16 +01:00
compiler_builtins.rs	rust: add intrinsics to fix -Os builds	2024-08-10 00:05:10 +02:00
exports.c	rust: replace <linux/module.h> with <linux/export.h> in rust/exports.c	2023-12-13 01:09:55 +01:00
helpers.c	Rust changes for v6.11	2024-07-27 13:44:54 -07:00
Makefile	rust: kbuild: fix export of bss symbols	2024-08-21 01:24:10 +02:00