From: Richard Patel <ripatel@wii.dev>
To: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
Cc: "kees@kernel.org" <kees@kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
"hpa@zytor.com" <hpa@zytor.com>,
"shuah@kernel.org" <shuah@kernel.org>,
"mingo@redhat.com" <mingo@redhat.com>,
"bp@alien8.de" <bp@alien8.de>,
"tglx@kernel.org" <tglx@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-kselftest@vger.kernel.org"
<linux-kselftest@vger.kernel.org>
Subject: Re: [PATCH 1/3] x86/shstk: ban ia32 sigreturn when shadow stack is enabled
Date: Fri, 9 Oct 2026 11:36:23 +0000 [thread overview]
Message-ID: <asjRt49FfzdP4pxk@wii.dev> (raw)
In-Reply-To: <f78ade122593ecdd686ec1b29340b0124b925c48.camel@intel.com>
On Thu, Oct 08, 2026 at 11:11:41PM +0000, Edgecombe, Rick P wrote:
> On Thu, 2026-10-08 at 22:47 +0000, Richard Patel wrote:
> > > But today setting EIP to an arbitrary point is fairly easy. But even in a
> > > future
> > > case of IBT enabled, shadow stack would still need enhancements for the
> > > normal
> > > 64 bit runtime to prevent this.
> >
> > What do you think of creating a shadow stack frame on signal delivery
> > and popping that on sigreturn? I suppose that would need siglongjmp
> > modifications and probably break CRIU. :(
>
> Yes I didn't know they did not parse the shadow stack signal frame
> appropriately. That is unfortunate. But we can still evolve the shadow stack ABI
> by adding new modes to the enable prctl if we want.
In the case of CRIU, they are not only parsing, but crafting their own
frames on the shadow stack. I suppose we can keep the kernel's parser
lenient so it works with older CRIU frames even after IBT enablement.
next prev parent reply other threads:[~2026-10-09 11:36 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-08 20:16 [PATCH 0/3] x86/shstk: ban ia32 sigreturn Richard Patel
2026-10-08 20:16 ` [PATCH 1/3] x86/shstk: ban ia32 sigreturn when shadow stack is enabled Richard Patel
2026-10-08 20:59 ` Edgecombe, Rick P
2026-10-08 21:50 ` Richard Patel
2026-10-08 22:34 ` Edgecombe, Rick P
2026-10-08 22:47 ` Richard Patel
2026-10-08 23:11 ` Edgecombe, Rick P
2026-10-08 23:29 ` Richard Patel
2026-10-09 11:36 ` Richard Patel [this message]
2026-10-08 20:16 ` [PATCH 2/3] selftests/x86: test shadow stack sigreturn protection Richard Patel
2026-10-08 20:16 ` [PATCH 3/3] selftests/x86: skip shstk tests where perf_event_open() fails Richard Patel
2026-10-08 21:00 ` [PATCH 0/3] x86/shstk: ban ia32 sigreturn Edgecombe, Rick P
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