Re: [RFC PATCH 00/11] Rust null block driver

From: Andreas Hindborg <nmi@metaspace.dk>
To: Luis Chamberlain <mcgrof@kernel.org>
Cc: "Jens Axboe" <axboe@kernel.dk>, "Christoph Hellwig" <hch@lst.de>,
	"Keith Busch" <kbusch@kernel.org>,
	"Damien Le Moal" <Damien.LeMoal@wdc.com>,
	"Hannes Reinecke" <hare@suse.de>,
	lsf-pc@lists.linux-foundation.org,
	rust-for-linux@vger.kernel.org, linux-block@vger.kernel.org,
	"Matthew Wilcox" <willy@infradead.org>,
	"Miguel Ojeda" <ojeda@kernel.org>,
	"Alex Gaynor" <alex.gaynor@gmail.com>,
	"Wedson Almeida Filho" <wedsonaf@gmail.com>,
	"Boqun Feng" <boqun.feng@gmail.com>,
	"Gary Guo" <gary@garyguo.net>,
	"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
	"Benno Lossin" <benno.lossin@proton.me>,
	"open list" <linux-kernel@vger.kernel.org>,
	gost.dev@samsung.com
Subject: Re: [RFC PATCH 00/11] Rust null block driver
Date: Mon, 08 May 2023 01:37:19 +0200	[thread overview]
Message-ID: <87mt2fae4i.fsf@metaspace.dk> (raw)
In-Reply-To: <ZFg0xPy0dbd1b0rP@bombadil.infradead.org>

Luis Chamberlain <mcgrof@kernel.org> writes:

> On Wed, May 03, 2023 at 11:06:57AM +0200, Andreas Hindborg wrote:
>> The statistics presented in my previous message [1] show that the C null block
>> driver has had a significant amount of memory safety related problems in the
>> past. 41% of fixes merged for the C null block driver are fixes for memory
>> safety issues. This makes the null block driver a good candidate for rewriting
>> in Rust.
>
> Curious, how long does it take to do an analysis like this? Are there efforts
> to automate this a bit more? We have efforts to use machine learning to
> evaluate stable candidate patches, we probably should be able to qualify
> commits as fixing "memory safety", I figure.
>
> Because what I'd love to see is if we can could easily obtain similar
> statistics for arbitrary parts of the kernel. The easiest way to break
> this down might be by kconfig symbol for instance, and then based on
> that gather more information about subsystems.
>

I spent around 4 hours with a spreadsheet and git. It would be cool if
that work could be automated. It's not always clear from the commit
heading that a commit is a fix. When it is clear that it is a fix, it
might not be clear what is fixed. I had to look at the diff quite a few
commits.

There is some work mentioning the ratio of memory safety issues fixed in
the kernel, but none of them go into details for specific subsystems as
far as I know. 20% of bugs fixed in stable Linux Kernel branches for
drivers are memory safety issues [1]. 65% of recent Linux kernel
vulnerabilities are memory safety issues [2]

> Then the rationale for considerating adopting rust bindings for certain areas
> of the kernel becomes a bit clearer.

As mentioned elsewhere in this thread there are other benefits from
deploying Rust than provable absence of memory safety issues.

Best regards
Andreas

[1] http://dx.doi.org/10.15514/ISPRAS-2018-30(6)-8
[2] https://lssna19.sched.com/event/RHaT/writing-linux-kernel-modules-in-safe-rust-geoffrey-thomas-two-sigma-investments-alex-gaynor-alloy