On Mon, Mar 17, 2025 at 10:23:56AM -0400, Tamir Duberstein wrote: > Throughout the tree, use the strict provenance APIs stabilized in Rust > 1.84.0[1]. Retain backwards-compatibility by introducing forwarding > functions at the `kernel` crate root along with polyfills for rustc < > 1.84.0. > > Use `#[allow(clippy::incompatible_msrv)]` to avoid warnings on rustc < > 1.84.0 as our MSRV is 1.78.0. > > In the `kernel` crate, enable the strict provenance lints on rustc >= > 1.84.0; do this in `lib.rs` rather than `Makefile` to avoid introducing > compiler flags that are dependent on the rustc version in use. > > Link: https://blog.rust-lang.org/2025/01/09/Rust-1.84.0.html#strict-provenance-apis [1] > Suggested-by: Benno Lossin <benno.lossin@xxxxxxxxx> > Link: https://lore.kernel.org/all/D8EIXDMRXMJP.36TFCGWZBRS3Y@xxxxxxxxx/ > Signed-off-by: Tamir Duberstein <tamird@xxxxxxxxx> I'm not convinced that the pros of this change outweigh the cons. I think this is going to be too confusing for the C developers who look at this code. > diff --git a/rust/kernel/uaccess.rs b/rust/kernel/uaccess.rs > index 719b0a48ff55..96393bcf6bd7 100644 > --- a/rust/kernel/uaccess.rs > +++ b/rust/kernel/uaccess.rs > @@ -226,7 +226,9 @@ pub fn read_raw(&mut self, out: &mut [MaybeUninit<u8>]) -> Result { > } > // SAFETY: `out_ptr` points into a mutable slice of length `len`, so we may write > // that many bytes to it. > - let res = unsafe { bindings::copy_from_user(out_ptr, self.ptr as *const c_void, len) }; > + let res = unsafe { > + bindings::copy_from_user(out_ptr, crate::with_exposed_provenance(self.ptr), len) > + }; > if res != 0 { > return Err(EFAULT); > } > @@ -264,7 +266,7 @@ pub fn read<T: FromBytes>(&mut self) -> Result<T> { > let res = unsafe { > bindings::_copy_from_user( > out.as_mut_ptr().cast::<c_void>(), > - self.ptr as *const c_void, > + crate::with_exposed_provenance(self.ptr), > len, > ) > }; That's especially true for cases like this. These are userspace pointers that are never dereferenced. It's not useful to care about provenance here. Alice
