Re: [PATCH v2 1/4] rust: uaccess: add userspace pointers

[Alice Ryhl]

On Thu, Feb 8, 2024 at 4:48 PM Alice Ryhl <aliceryhl@xxxxxxxxxx> wrote:
> +    /// Reads the entirety of the user slice, appending it to the end of the
> +    /// provided buffer.
> +    ///
> +    /// Fails with `EFAULT` if the read encounters a page fault.
> +    pub fn read_all(mut self, buf: &mut Vec<u8>) -> Result<()> {
> +        buf.try_reserve(self.length)?;
> +
> +        // SAFETY: The call to `try_reserve` was successful, so the spare
> +        // capacity is at least `self.length` bytes long.
> +        unsafe { self.read_raw(buf.spare_capacity_mut().as_mut_ptr().cast(), self.length)? };
> +
> +        // SAFETY: Since the call to `read_raw` was successful, so the next
> +        // `len` bytes of the vector have been initialized.
> +        unsafe { buf.set_len(buf.len() + self.length) };
> +        Ok(())
> +    }

There's a bug here, since read_raw changes self.length. It will be
fixed in the next version.

Alice