linux-kernel - Re: [PATCH v5 05/18] rust: str: introduce `kstrtobool` function

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: <87o6shdmg7.fsf@t14s.mail-host-address-is-not-set>
Date: Fri, 15 Aug 2025 10:21:44 +0200
From: Andreas Hindborg <a.hindborg@...nel.org>
To: Alice Ryhl <aliceryhl@...gle.com>
Cc: Boqun Feng <boqun.feng@...il.com>, Miguel Ojeda <ojeda@...nel.org>, Alex
 Gaynor <alex.gaynor@...il.com>, Gary Guo <gary@...yguo.net>, Björn Roy
 Baron <bjorn3_gh@...tonmail.com>, Benno Lossin <lossin@...nel.org>, Trevor
 Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>, Jens Axboe
 <axboe@...nel.dk>, Breno Leitao <leitao@...ian.org>,
 linux-block@...r.kernel.org, rust-for-linux@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 05/18] rust: str: introduce `kstrtobool` function

"Alice Ryhl" <aliceryhl@...gle.com> writes:

> On Fri, Aug 15, 2025 at 09:30:40AM +0200, Andreas Hindborg wrote:

<cut>

>> +pub fn kstrtobool(string: &CStr) -> Result<bool> {
>> +    let mut result: bool = false;
>> +
>> +    // SAFETY: `string` is a valid null-terminated C string, and `result` is a valid
>> +    // pointer to a bool that we own.
>> +    let ret =
>> +        unsafe { bindings::kstrtobool(string.as_char_ptr(), core::ptr::from_mut(&mut result)) };
>
> Using ptr::from_mut here seesm excessive IMO. I think that function
> makes sense when it replaces an explicit `as` cast, but now when it can
> be done by a coercion. This is perfectly readable:
>
> let ret = unsafe { bindings::kstrtobool(string.as_char_ptr(), &mut result) };
>
> Or if you insist, you could directly create a raw pointer:
>
> let ret = unsafe { bindings::kstrtobool(string.as_char_ptr(), &raw mut result) };

Oh, I'll do the implicit coercion then.

I was using `&mut result as *mut bool` but clippy told me to do the `from_mut`
instead.


Best regards,
Andreas Hindborg