From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-108-mta150.mxroute.com (mail-108-mta150.mxroute.com [136.175.108.150]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4BC774D17AF for ; Fri, 9 Oct 2026 11:36:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=136.175.108.150 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791545813; cv=none; b=V3f9lVtBj06svaJ/tD4bqum5kcrCQkgyjzSzSnpA4QWc3gzMrP+vCQKNFk/EbVZIlCyRzo4Fo1lU4f7LkT0DP9jpLk+Fsvg/+nT0AzEG3B617y8n6i2C8EQK+Kns9Gx/mVOZjnEFztejS0ZG5yUjtGFhbwT61KMJwyjx+Cw1Zoc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791545813; c=relaxed/simple; bh=72mb7nDzWwJbkkQTYO35saRlKYr1LDO6zGEKsn74JQE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=hNf7eYvxhXc1M2BlP0gv4TeSMGhvpft2JuJ/FUT2BvT8X8y8wxsETS0hYG5BgIGljikztYvOxqqMZPPMwVVB64Lvt7raZlOxocdnZPYT2CWmN7Y0LyRee3qsjIThj5Nbs/iRLoLg4cY7k/yJIJ26jP4SxekgZnwUOnBkQ75pA30= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=wii.dev; spf=pass smtp.mailfrom=wii.dev; dkim=pass (2048-bit key) header.d=wii.dev header.i=@wii.dev header.b=JiQfopHq; arc=none smtp.client-ip=136.175.108.150 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=wii.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=wii.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=wii.dev header.i=@wii.dev header.b="JiQfopHq" Received: from filter006.mxroute.com ([136.175.111.3] filter006.mxroute.com) (Authenticated sender: mN4UYu2MZsgR) by mail-108-mta150.mxroute.com (ZoneMTA) with ESMTPSA id 1a1207374be00028b2.009 for (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384); Fri, 09 Oct 2026 11:36:39 +0000 X-Zone-Loop: fc265d78d85525497cd61ac2ffbe90250f3e56d0bbc0 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=wii.dev; s=x; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID:Subject:Cc :To:From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=1WzxT4EeKabTRMvEusYxWV+LdwJUl+4VKsG0DruUDyI=; b=JiQfopHqe0hsa+NxuKZC9XnAcI MhLkXtp4c97TencxVnX7W1SKkieszlUcY2MdxwQ/bZ9Yszt8oRvYTB/sV9CB4T0VfK/ZT+k9uUJRY Bx5PnIQ3+ZTxBxjX1Ish6zQvT9717AwQMEK6+ExkhdFGJRSYO9pRTRcTJBWesInjnHErOR8yMr1gx rX1a0Pkuc8IzaX0+O1Vh0EUl8AMS5BLPN142XPU5PV4AGsqxCWOwocBdU+zQjyITj+NlkGAJEB7s7 wq26StDciAXl4EtW+SG4JlhUPkAmRnWoUduo6PUZRZfBYYtBXCRtOOMb9uuZE5ZhXmFHY4rMU0ImX tCaV5LwA==; Date: Fri, 9 Oct 2026 11:36:23 +0000 From: Richard Patel To: "Edgecombe, Rick P" Cc: "kees@kernel.org" , "x86@kernel.org" , "dave.hansen@linux.intel.com" , "hpa@zytor.com" , "shuah@kernel.org" , "mingo@redhat.com" , "bp@alien8.de" , "tglx@kernel.org" , "linux-kernel@vger.kernel.org" , "linux-kselftest@vger.kernel.org" Subject: Re: [PATCH 1/3] x86/shstk: ban ia32 sigreturn when shadow stack is enabled Message-ID: References: <20261008201610.1003569-1-ripatel@wii.dev> <20261008201610.1003569-2-ripatel@wii.dev> <6deab6fec99c65408a19b9036d67ce7f1fab54b5.camel@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Authenticated-Id: ripatel@wii.dev 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.