linux-kernel - Re: [PATCH RFC RFT v2 2/5] fork: Add shadow stack support to clone3()

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Message-ID: <ZVYfO/yqRtuRYaJA@arm.com>
Date:   Thu, 16 Nov 2023 13:55:07 +0000
From:   "Szabolcs.Nagy@....com" <Szabolcs.Nagy@....com>
To:     Mark Brown <broonie@...nel.org>
Cc:     "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
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Subject: Re: [PATCH RFC RFT v2 2/5] fork: Add shadow stack support to clone3()

The 11/16/2023 12:33, Mark Brown wrote:
> On Thu, Nov 16, 2023 at 10:32:06AM +0000, Szabolcs.Nagy@....com wrote:
> > i guess the tricky case is stack!=0 && shadow_stack_size==0:
> > the user may want a new shadow stack with default size logic,
> > or (with !CLONE_VM || CLONE_VFORK) wants to use the existing
> > shadow stack from the parent.
>
> If shadow_stack_size is 0 then we're into clone() behaviour and doing
> the default/implicit handling which is to do exactly what the above
> describes.

to be clear does clone with flags==CLONE_VM|CLONE_VFORK always
use the parent shadow stack independently of the stack argument?
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