netdev - Re: [PATCH net-next v2 5/6] rust: Add read_poll

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Message-ID: <df2c9ea8-fa3a-416e-affd-b3891b2ab3f7@lunn.ch>
Date: Tue, 8 Oct 2024 19:16:42 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
Cc: Boqun Feng <boqun.feng@...il.com>, Alice Ryhl <aliceryhl@...gle.com>,
	FUJITA Tomonori <fujita.tomonori@...il.com>, netdev@...r.kernel.org,
	rust-for-linux@...r.kernel.org, hkallweit1@...il.com,
	tmgross@...ch.edu, ojeda@...nel.org, alex.gaynor@...il.com,
	gary@...yguo.net, bjorn3_gh@...tonmail.com, benno.lossin@...ton.me,
	a.hindborg@...sung.com, anna-maria@...utronix.de,
	frederic@...nel.org, tglx@...utronix.de, arnd@...db.de,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v2 5/6] rust: Add read_poll_timeout function

On Tue, Oct 08, 2024 at 03:14:05PM +0200, Miguel Ojeda wrote:
> On Tue, Oct 8, 2024 at 2:13 PM Andrew Lunn <andrew@...n.ch> wrote:
> >
> > As far as i see, might_sleep() will cause UAF where there is going to
> > be a UAF anyway. If you are using it correctly, it does not cause UAF.
> 
> This already implies that it is an unsafe function (in general, i.e.
> modulo klint, or a way to force the user to have to write `unsafe`
> somewhere else, or what I call ASHes -- "acknowledged soundness
> holes").
> 
> If we consider as safe functions that, if used correctly, do not cause
> UB, then all functions would be safe.

>From what i hear, klint is still WIP. So we have to accept there will
be bad code out there, which will UAF. We want to find such bad code,
and the easiest way to find it at the moment is to make it UAF as fast
as possible. might_sleep() does that, __might_sleep() does not, and
using neither is the slowest way.

	Andrew