Re: [PATCH 1/2] rust: uaccess: add UserSliceWriter::clear()

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] rust: uaccess: UserSliceWriter::clear() missing #[inline] attribute
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commit 3db28db591b863b3412fb9ace61521aee539bc5a
Author: Deborah Brouwer <deborah.brouwer@collabora.com>

rust: uaccess: add UserSliceWriter::clear()

This commit adds a clear() method to UserSliceWriter to zero out the remaining
buffer in userspace, preventing uninitialized memory consumption. It also
introduces a rust_helper_clear_user() wrapper for the architecturally defined
clear_user() C function so it can be called from Rust.

> diff --git a/rust/kernel/uaccess.rs b/rust/kernel/uaccess.rs
> index f1aecda7a90ce..6838e7f90abb5 100644
> --- a/rust/kernel/uaccess.rs
> +++ b/rust/kernel/uaccess.rs
[ ... ]
> @@ -638,6 +638,29 @@ pub fn write<T: AsBytes>(&mut self, value: &T) -> Result {
>      pub fn write_truncated<T: AsBytes>(&mut self, value: &T) -> Result<usize> {
>          self.write_slice_partial(value.as_bytes(), 0)
>      }
> +
> +    /// Zeros remaining bytes in the userspace buffer.
> +    ///
> +    /// Fails with [`EFAULT`] if the userspace memory cannot be cleared.
> +    pub fn clear(&mut self) -> Result {

[Severity: Low]
This isn't a bug, but should this method be marked with the #[inline]
attribute? Small wrapper functions in abstractions that primarily forward to
C bindings (like bindings::clear_user in this case) typically include the
#[inline] annotation as recommended by the Rust subsystem coding guidelines.

> +        let len = self.length;
> +
> +        if len == 0 {
> +            return Ok(());
> +        }
> +        // SAFETY: `clear_user` checks the userspace address and range and handles
> +        // faults when accessing userspace memory
> +        let res = unsafe { bindings::clear_user(self.ptr.as_mut_ptr(), len) };

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Sashiko AI review · https://sashiko.dev/#/patchset/20261014-b4-dev_query_fixes-v1-0-92043100b472@collabora.com?part=1