Re: [TECH TOPIC] Improving resource ownership and life-time in linux device drivers

[Julia Lawall <julia.lawall@inria.fr>]

On Wed, 9 Aug 2023, Bartosz Golaszewski wrote:

> Hi!
>
> I submitted this proposal on time using the website but forgot about
> sending it here too. Hope that's alright. The abstract follows.
>
> Bartosz Golaszewski
>
> --
>
> Recently there have been several talks about issues with object
> ownership in device drivers, use-after-free bugs and problems with
> handling hot unplug events in certain subsystems.
>
> First Laurent Pinchart revisited an older discussion about the harmful
> side-effects of devres helpers during LPC 2022[1]. I then went down
> that rabbit hole only to discover a whole suite of issues, not really
> linked to devres in any way but rather mostly caused by the way
> subsystems and drivers mix reference counted resources with regular
> ones[2]. This year Wolfram Sang continued the research and presented
> even more vulnerable subsystems as well as some potential remedies
> during his talk at the EOSS 2023 in Prague[3].
>
> I have since experimented with several approaches and would like to
> present some updates on this subject. During this talk I plan to jump
> straight into presenting concrete ideas and timelines for improving
> the driver model and introducing some unification in the way
> subsystems handle driver data. While this is a significant effort
> spanning multiple device subsystems that will need to be carried out
> in many phases over what will most likely be years, without addressing
> the problems, we'll be left with many parts of the kernel not being
> able to correctly handle simple driver unbinds.
>
> [1] https://lpc.events/event/16/contributions/1227/
> [2] https://fosdem.org/2023/schedule/event/devm_kzalloc/
> [3] https://eoss2023.sched.com/event/1LcPP/subsystems-with-object-lifetime-issues-in-the-embedded-case-wolfram-sang-sang-engineering-renesas

I will be very interested in seeing this talk.

julia