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: <DADKRV2K4A5I.3UAZF5O9EW6R8@kernel.org>
Date: Wed, 04 Jun 2025 09:36:59 +0200
From: "Benno Lossin" <lossin@...nel.org>
To: "Alice Ryhl" <aliceryhl@...gle.com>
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 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?

---
Cheers,
Benno