alt.hn

5/9/2026 at 9:14:05 AM

Killswitch: Per-function short-circuit mitigation primitive

 https://lwn.net/ml/all/20260507070547.2268452-1-sashal@kernel.org/

by signa11

5/9/2026 at 2:13:49 PM

Super cool. Also, love reading high quality linux patches. I think many, myself previously included, are afraid to even read the kernel source as one thinks it must be super complex. Of course some parts really are. However, the code is honestly of such high quality. I also highly value that feeling of realizing something once thought 'arcane' was actually only made by other humans, and it is legal to go read it and learn from it.

by logdahl

5/9/2026 at 12:08:18 PM

Clever! I know some will say it's like closing the barn door after the horse left, but having this in place to mitigate future vulnerabilities will be handy.

by PeterWhittaker

5/9/2026 at 12:31:42 PM

ok, but what kind of nefarious use case will it enable if it is accessible to malfeasance.

by cyanydeez

5/9/2026 at 2:44:13 PM

I may be wrong, but on a correctly-configured system, one would have to have root access to act nefariously. Since this is intended to prevent exploitation of vulnerabilities that enable privilege escalation, it feels like a net win.

by PeterWhittaker

5/9/2026 at 12:48:36 PM

I guess it could disable the killswitch

by ObscureScience

5/9/2026 at 2:25:56 PM

besides that.

by cyanydeez

5/9/2026 at 5:16:53 PM

Could something like this also be done via BPF?

by Phelinofist

5/9/2026 at 7:17:05 PM

this sounds simple, but not running a function doesn't on its own mean safe behavior, if the caller code wasn't written keeping in mind this novel potential refusal as an outcome

still i believe this is the right direction

by DoctorOetker

5/9/2026 at 12:47:44 PM

If I'm a malicious actor that gets root, can I killswitch the killswitch?

by frumiousirc

5/9/2026 at 12:55:49 PM

you're on the other side of the secure door already

killswitch is to prevent you from gaining root

by htmlenjoyye

5/9/2026 at 2:01:43 PM

Once you’ve got root, you don’t need to exploit compromised code to do whatever you want.

by cowthulhu

5/9/2026 at 8:01:23 PM

LSMs say otherwise

by LoganDark

5/10/2026 at 7:21:23 AM

ring0 loadable kernel modules disagree.

by worthless-trash

5/11/2026 at 12:45:32 AM

Only to the extent there is not a deeply embedded core, of course. Or SMM

by LoganDark

5/11/2026 at 9:55:25 AM

Neither of those are LSM though right ?

by worthless-trash

5/9/2026 at 6:37:47 PM

Or malloc(), or open()... They kind of discussing it in the thread on how to prevent this from a malicious actor (or from footgunning yourself), but my understanding it is not all that plain and simple...

by tandr

5/9/2026 at 1:47:17 PM

Better tooling for kpatch would be nice tho

IIRC canonical makes patches for official ubuntu kernels but acts like a Chinese restaurant (closed kitchen, orders come in through a small hatch behind the counter)

by tosti

5/9/2026 at 7:18:28 PM

Is there any library that does this safely for user-mode and is currently used in production ?

by xuhu

5/9/2026 at 4:38:33 PM

>Assisted-by: Claude:claude-opus-4-7

by luka598

5/9/2026 at 7:19:49 PM

The author has an @kernel.org address, and has been a regular Linux contributor for over a decade. I'll give him the benefit of the doubt. It's easy to write high quality AI-assisted code (harder than writing vibe-coded slop, but still easier than writing every line of code yourself).

Edit: This also reminds me that I've begun to judge projects by whether the developer has public code from before AI. I'm more likely to trust their new code. Which causes me concern about the pipeline for new developers...how am I supposed to know a new user on Github has enough understanding of how software works to be shipping software? It used to be that if a new project by a new dev had good docs, some kind of test coverage, and a coherent git history, I could infer some level of quality. Not true, now, so I probably move on and look for something from someone with a pre-AI track record.

by SwellJoe

5/9/2026 at 4:53:51 PM

As an ai critic myself, so what?

by Brian_K_White

5/9/2026 at 6:17:18 PM

What about inlined functions?

by ainto

5/9/2026 at 6:29:28 PM

As addressed in the article ("Choosing the right target"):

> Pick the *highest-level* entry point that contains the bug

by Rygian