linux-kernel - Re: [PATCH 3/3] rust: add WMI abstractions

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <670cab36-3d32-4769-8a3c-a5d3e1bdd74a@foxido.dev>
Date: Fri, 9 Jan 2026 14:01:16 +0300
From: Gladyshev Ilya <foxido@...ido.dev>
To: Kari Argillander <kari.argillander@...il.com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>,
 Miguel Ojeda <ojeda@...nel.org>, Boqun Feng <boqun.feng@...il.com>,
 Gary Guo <gary@...yguo.net>, Benno Lossin <lossin@...nel.org>,
 Andreas Hindborg <a.hindborg@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>,
 Trevor Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>,
 Tamir Duberstein <tamird@...il.com>, Armin Wolf <W_Armin@....de>,
 platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
 rust-for-linux@...r.kernel.org, linux-acpi@...r.kernel.org, foxido@...ido.dev
Subject: Re: [PATCH 3/3] rust: add WMI abstractions

On 1/8/26 23:48, Kari Argillander wrote:
> On Wed, 7 Jan 2026 at 22:56, Gladyshev Ilya <foxido@...ido.dev> wrote:
> <snip>
> 
>> +impl DeviceId {
>> +    /// Constructs new DeviceId from GUID string.
>> +    pub const fn new(guid: &[u8; bindings::UUID_STRING_LEN as usize]) -> Self {
>> +        // SAFETY: FFI type is valid to be zero-initialized.
>> +        let mut inner: bindings::wmi_device_id = unsafe { MaybeUninit::zeroed().assume_init() };
>> +
>> +        build_assert!(inner.guid_string.len() == bindings::UUID_STRING_LEN as usize + 1);
>> +
>> +        // SAFETY: It's safe to copy UUID_STRING_LEN, because we validated lengths.
>> +        // Also we leave last byte zeroed, so guid_string is valid C string.
>> +        unsafe {
>> +            ::core::ptr::copy_nonoverlapping(
>> +                guid.as_ptr(),
>> +                &raw mut inner.guid_string[0],
>> +                bindings::UUID_STRING_LEN as usize,
>> +            );
>> +        }
> 
> Just use while here so no unsafe is needed at all. Then probably patch
> 1/3 is not needed.

Overall this operation is still unsafe because we are constructing C 
string in FFI object. So for me avoiding `unsafe` via less readable 
(imo) loop will just mask unsafe operation without any real benefits.

Ideally this function should receive c string and just validate it's 
length, but IIRC I had troubles with build-time validation of C string 
length

>> +
>> +        Self(inner)
>> +    }
>> +}