* Fwd: [PATCH] rust: document safety requirements for fmt::Arguments dereference
[not found] <CAO0d=D-+p2QbA9bxOSO0rd185GY5Pe0ruq=A=hcgTvovC3d1oA@mail.gmail.com>
@ 2025-12-14 13:11 ` Riccardo Adami
2025-12-17 20:38 ` Alice Ryhl
0 siblings, 1 reply; 2+ messages in thread
From: Riccardo Adami @ 2025-12-14 13:11 UTC (permalink / raw)
To: rust-for-linux
---------- Forwarded message ---------
Da: Riccardo Adami <riccioadami@gmail.com>
Date: dom 14 dic 2025 alle ore 13:54
Subject: [PATCH] rust: document safety requirements for fmt::Arguments
dereference
To: <rust-for-linux@vger.kernel.org>
The `unsafe` dereference of `*ptr.cast::<fmt::Arguments<'_>>()` in
`rust_fmt_argument` is safe because `ptr` is provided by the kernel
formatting path for the `%pA` specifier and during `vsnprintf`
processing.
It always points to a valid `fmt::Arguments` value created by the caller.
The value lives at least for the duration of this call and it is only
read here and not stored or accessed after returning.
--- a/rust/kernel/print_dot_rs
+++ b/rust/kernel/print_dot_rs
@@
- // SAFETY: TODO.
+ // SAFETY: `ptr` is provided by the kernel formatting path for the `%pA`
+ // specifier during `vsnprintf` processing and always points to a valid
+ // `fmt::Arguments` value created by the caller. The value lives at least
+ // for the duration of this call and is only read here. It is not stored
+ // or accessed after returning, so dereferencing it is safe.
let _ = w.write_fmt(unsafe { *ptr.cast::<fmt::Arguments<'_>>() });
Thanks
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: Fwd: [PATCH] rust: document safety requirements for fmt::Arguments dereference
2025-12-14 13:11 ` Fwd: [PATCH] rust: document safety requirements for fmt::Arguments dereference Riccardo Adami
@ 2025-12-17 20:38 ` Alice Ryhl
0 siblings, 0 replies; 2+ messages in thread
From: Alice Ryhl @ 2025-12-17 20:38 UTC (permalink / raw)
To: Riccardo Adami; +Cc: rust-for-linux
On Sun, Dec 14, 2025 at 02:11:08PM +0100, Riccardo Adami wrote:
> ---------- Forwarded message ---------
> Da: Riccardo Adami <riccioadami@gmail.com>
> Date: dom 14 dic 2025 alle ore 13:54
> Subject: [PATCH] rust: document safety requirements for fmt::Arguments
> dereference
> To: <rust-for-linux@vger.kernel.org>
>
>
> The `unsafe` dereference of `*ptr.cast::<fmt::Arguments<'_>>()` in
> `rust_fmt_argument` is safe because `ptr` is provided by the kernel
> formatting path for the `%pA` specifier and during `vsnprintf`
> processing.
> It always points to a valid `fmt::Arguments` value created by the caller.
> The value lives at least for the duration of this call and it is only
> read here and not stored or accessed after returning.
>
>
> --- a/rust/kernel/print_dot_rs
> +++ b/rust/kernel/print_dot_rs
> @@
> - // SAFETY: TODO.
> + // SAFETY: `ptr` is provided by the kernel formatting path for the `%pA`
> + // specifier during `vsnprintf` processing and always points to a valid
> + // `fmt::Arguments` value created by the caller. The value lives at least
> + // for the duration of this call and is only read here. It is not stored
> + // or accessed after returning, so dereferencing it is safe.
> let _ = w.write_fmt(unsafe { *ptr.cast::<fmt::Arguments<'_>>() });
>
> Thanks
This patch does not appear to be formatted correctly. Can you try using
git send-email?
Alice
^ permalink raw reply [flat|nested] 2+ messages in thread
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2025-12-14 13:11 ` Fwd: [PATCH] rust: document safety requirements for fmt::Arguments dereference Riccardo Adami
2025-12-17 20:38 ` Alice Ryhl
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