linux-kernel - Re: [PATCH RFT v8 4/9] fork: Add shadow stack support to clone3()

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Message-ID: <067b890c-b879-4188-b428-cfadcc524630@sirena.org.uk>
Date: Fri, 16 Aug 2024 16:30:15 +0100
From: Mark Brown <broonie@...nel.org>
To: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
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Subject: Re: [PATCH RFT v8 4/9] fork: Add shadow stack support to clone3()

On Fri, Aug 16, 2024 at 02:52:28PM +0000, Edgecombe, Rick P wrote:
> On Fri, 2024-08-16 at 09:44 +0100, Catalin Marinas wrote:

> > BTW, since it's the parent setting up the shadow stack in its own
> > address space before forking, I think at least the read can avoid
> > access_remote_vm() and we could do it earlier, even before the new
> > process is created.

> Hmm. Makes sense. It's a bit racy since the parent could consume that token from
> another thread, but it would be a race in any case.

So it sounds like we might be coming round to this?  I've got a new
version that verifies the VM_SHADOW_STACK good to go but if we're going
to switch back to consuming the token in the parent context I may as
well do that.  Like I said in the other mail I'd rather not flip flop
on this.

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