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Date:   Sat, 4 Nov 2023 17:02:00 -0400
From:   Sasha Levin <sashal@kernel.org>
To:     Benno Lossin <benno.lossin@proton.me>
Cc:     stable@vger.kernel.org, Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Alice Ryhl <aliceryhl@google.com>, Gary Guo <gary@garyguo.net>,
        Andreas Hindborg <a.hindborg@samsung.com>,
        Martin Rodriguez Reboredo <yakoyoku@gmail.com>,
        rust-for-linux@vger.kernel.org
Subject: Re: backport 0b4e3b6f6b79 and 35cad617df2e
Message-ID: <ZUaxSDabYeRN7TPv@sashalap>
References: <1760daa6-7245-4d01-bb89-388c472ec5ed@proton.me>
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On Fri, Nov 03, 2023 at 09:57:46PM +0000, Benno Lossin wrote:
>Hi,
>
>I noticed that without commit 0b4e3b6f6b79 ("rust: types: make `Opaque`
>be `!Unpin`") the `Opaque` type has an unsound API:
>The `Opaque` type is designed to wrap C types, hence it is often used to
>convert raw pointers to references in Rust. Normally `&mut` references
>are unique, but for `&mut Opaque<T>` this is should not be the case,
>since C also has pointers to the object. The way to disable the
>uniqueness guarantee for `&mut` in Rust is to make the type `!Unpin`.
>This is accomplished by the given commit above. At the time of creating
>that patch however, we did not consider this unsoundness issue.
>
>For this reason I propose to backport the commit 0b4e3b6f6b79.
>The only affected version is 6.5. No earlier version is affected, since
>the `Opaque` type does not exist in 6.1. Newer versions are also
>unaffected, since the patch is present in 6.6.
>
>Additionally I also propose to backport commit 35cad617df2e ("rust: make
>`UnsafeCell` the outer type in `Opaque`") to 6.5, as this is a
>prerequisite of 0b4e3b6f6b79.

Queued up, thanks!

-- 
Thanks,
Sasha