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

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Message-ID: <fc40c53d-341f-4e2f-b9a4-49f380a1e926@sirena.org.uk>
Date: Fri, 16 Aug 2024 16:46:44 +0100
From: Mark Brown <broonie@...nel.org>
To: Catalin Marinas <catalin.marinas@....com>
Cc: "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 04:29:13PM +0100, Catalin Marinas wrote:
> On Fri, Aug 16, 2024 at 11:51:57AM +0100, Mark Brown wrote:

> > I change back to parsing the token in the parent but I don't want to end
> > up in a cycle of bouncing between the two implementations depending on
> > who's reviewed the most recent version.

> You and others spent a lot more time looking at shadow stacks than me.
> I'm not necessarily asking to change stuff but rather understand the
> choices made.

I'm a little ambivalent on this - on the one hand accessing the child's
memory is not a thing of great beauty but on the other hand it does
make the !CLONE_VM case more solid.  My general instinct is that the
ugliness is less of an issue than the "oh, there's a gap there" stuff
with the !CLONE_VM case since it's more "why are we doing that?" than
"we missed this".

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