linux-kernel - Re: [PATCH v3 1/2] rust: irq: add support for request

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: <CAH5fLggaX18dAzWqLLkn9ii+hpu14u4aY5vd=kSCkk6LvsW-eA@mail.gmail.com>
Date: Wed, 4 Jun 2025 09:48:46 +0200
From: Alice Ryhl <aliceryhl@...gle.com>
To: Benno Lossin <lossin@...nel.org>
Cc: Daniel Almeida <daniel.almeida@...labora.com>, Miguel Ojeda <ojeda@...nel.org>, 
	Alex Gaynor <alex.gaynor@...il.com>, Boqun Feng <boqun.feng@...il.com>, 
	Gary Guo <gary@...yguo.net>, Björn Roy Baron <bjorn3_gh@...tonmail.com>, 
	Benno Lossin <benno.lossin@...ton.me>, Andreas Hindborg <a.hindborg@...nel.org>, 
	Trevor Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Rafael J. Wysocki" <rafael@...nel.org>, 
	Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org, 
	rust-for-linux@...r.kernel.org
Subject: Re: [PATCH v3 1/2] rust: irq: add support for request_irq()

On Wed, Jun 4, 2025 at 9:37 AM Benno Lossin <lossin@...nel.org> wrote:
>
> On Mon Jun 2, 2025 at 5:20 PM CEST, Alice Ryhl wrote:
> > On Wed, May 14, 2025 at 10:04:43PM +0200, Benno Lossin wrote:
> >> On Wed May 14, 2025 at 9:20 PM CEST, Daniel Almeida wrote:
> >> > +                )
> >> > +            });
> >> > +
> >> > +            if res.is_err() {
> >> > +                // SAFETY: We are returning an error, so we can destroy the slot.
> >> > +                unsafe { core::ptr::drop_in_place(addr_of_mut!((*slot).handler)) };
> >> > +            }
> >> > +
> >> > +            res
> >> > +        };
> >> > +
> >> > +        // SAFETY:
> >> > +        // - if this returns Ok, then every field of `slot` is fully
> >> > +        // initialized.
> >> > +        // - if this returns an error, then the slot does not need to remain
> >> > +        // valid.
> >> > +        unsafe { pin_init_from_closure(closure) }
> >>
> >> Please don't use `pin_init_from_closure`, instead do this:
> >>
> >>     pin_init!(Self {
> >>         irq,
> >>         handler,
> >>         _pin: PhantomPinned
> >>     })
> >>     .pin_chain(|this| {
> >>         // SAFETY: TODO: correct FFI safety requirements
> >>         to_result(unsafe {
> >>             bindings::request_irq(...)
> >>         })
> >>     })
> >>
> >> The `pin_chain` function is exactly for this use-case, doing some
> >> operation that might fail after initializing & it will drop the value
> >> when the closure fails.
> >
> > No, that doesn't work. Using pin_chain will call free_irq if the call to
> > request_irq fails, which is incorrect.
>
> Good catch. That's a bit annoying then... I wonder if there is a
> primitive missing in pin-init that could help with this... Any ideas?

I believe initializers for underscore fields would do it. We could
potentially abuse the _pin field, but frankly I think that's too
confusing to the reader.

Alice