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References: <20230730012905.643822-1-boqun.feng@gmail.com> <20230730012905.643822-2-boqun.feng@gmail.com>
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From:   Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Date:   Sun, 30 Jul 2023 22:43:44 +0200
Message-ID: <CANiq72nf4N_HXOAZupM_Gq=c0jg-L__YUQtx4fSRpNuRqt4JAw@mail.gmail.com>
Subject: Re: [PATCH 1/3] rust: allocator: Prevent mis-aligned allocation
To:     Boqun Feng <boqun.feng@gmail.com>,
        =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>
Cc:     rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Gary Guo <gary@garyguo.net>,
        Benno Lossin <benno.lossin@proton.me>,
        Martin Rodriguez Reboredo <yakoyoku@gmail.com>,
        Alice Ryhl <aliceryhl@google.com>,
        Dariusz Sosnowski <dsosnowski@dsosnowski.pl>,
        Geoffrey Thomas <geofft@ldpreload.com>,
        Fox Chen <foxhlchen@gmail.com>,
        John Baublitz <john.m.baublitz@gmail.com>,
        Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Hyeonggon Yoo <42.hyeyoo@gmail.com>,
        Kees Cook <keescook@chromium.org>, stable@vger.kernel.org,
        Andreas Hindborg <nmi@metaspace.dk>
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On Sun, Jul 30, 2023 at 3:29=E2=80=AFAM Boqun Feng <boqun.feng@gmail.com> w=
rote:
>
> +// Note: Although these are *safe* functions, but they are only generate=
d at
> +// `GlobalAlloc` callsites, hence we assume the parameters obey the same
> +// `GlobalAlloc` function safety requirements: size and align should for=
m a
> +// valid layout, and size is greater than 0.

Thanks for adding all the `// SAFETY` comments here Boqun!

Bj=C3=B6rn, do they look good to you? (since you fixed the issue in the com=
piler)

On this comment in particular, "generated at `GlobalAlloc` callsites"
sounds a bit confusing to me. Would "... called by the compiler with
parameters that obey ..." make sense? Or does the sentence refer to
the normal case (i.e. when the functions are generated)? Anyway, it is
not a big deal.

Cheers,
Miguel