linux/rust
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
..
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