Re: [PATCH] killswitch: add per-function short-circuit mitigation primitive

[Sasha Levin <sashal@kernel.org>]

On Fri, May 08, 2026 at 04:49:25PM -0700, Andrew Morton wrote:
>On Fri, 8 May 2026 17:47:04 -0400 Sasha Levin <sashal@kernel.org> wrote:
>
>> >> 19 files changed, 1451 insertions(+), 1 deletion(-)
>> >
>> >wowzers.  I'm looking at samples/livepatch/livepatch-sample.c wondering
>> >"why"?
>>
>> Yup, a bit chunky, but over half of it is documentation and testing, and the
>> actual functional code is largely the securityfs interface.
>
>So we can't use livepatch here?

I might have misunderstood your original question.

Livepatch is great when you have one. The problem is getting one...

To get a livepatch, somebody has to write the fix, build it against the exact
kernel you're running (for distros, thats hundreds of different
kernel/arch/flavor combinations), sign it, and get it onto every machine.

Most regular users won't be able to do it on their own because of secure boot
limitations, so they depend on their vendor to provide them with one.

Yes, you could write a livepatch that just stubs the function out, same end
state as killswitch, but you still have to build, sign, and ship a module per
kernel to do it

Killswitch would be just a single write to /sys which an ordinary user can do
to mitigate a critical issue immediately.

-- 
Thanks,
Sasha