linux-kernel - Re: CVE-2023-52514: x86/reboot: VMCLEAR active VMCSes before emergency reboot

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Message-ID: <20240311161544.GS86322@google.com>
Date: Mon, 11 Mar 2024 16:15:44 +0000
From: Lee Jones <lee@...nel.org>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Michal Hocko <mhocko@...e.com>, cve@...nel.org,
	linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Juergen Gross <jgross@...e.com>,
	Andrew Cooper <Andrew.Cooper3@...rix.com>
Subject: Re: CVE-2023-52514: x86/reboot: VMCLEAR active VMCSes before
 emergency reboot

On Mon, 11 Mar 2024, Sean Christopherson wrote:

> On Mon, Mar 11, 2024, Lee Jones wrote:
> > On Mon, 11 Mar 2024, Michal Hocko wrote:
> > 
> > > On Sat 02-03-24 22:52:59, Greg KH wrote:
> > > > Description
> > > > ===========
> > > > 
> > > > In the Linux kernel, the following vulnerability has been resolved:
> > > > 
> > > > x86/reboot: VMCLEAR active VMCSes before emergency reboot
> > > > 
> > > > VMCLEAR active VMCSes before any emergency reboot, not just if the kernel
> > > > may kexec into a new kernel after a crash.  Per Intel's SDM, the VMX
> > > > architecture doesn't require the CPU to flush the VMCS cache on INIT.  If
> > > > an emergency reboot doesn't RESET CPUs, cached VMCSes could theoretically
> > > > be kept and only be written back to memory after the new kernel is booted,
> > > > i.e. could effectively corrupt memory after reboot.
> > > > 
> > > > Opportunistically remove the setting of the global pointer to NULL to make
> > > > checkpatch happy.
> > > > 
> > > > The Linux kernel CVE team has assigned CVE-2023-52514 to this issue.
> > > 
> > > I do not really see the security aspect of this fix. Guests systems
> > > shouldn't be able to trigger host reboot nor any untrusted entity should
> > > on the host either or this would be a serious security hole.
> 
> And not just any reboot either, this only comes into play with something like
> `reboot -f`.  Not to mention the impact of the bug is ridiculously theroetical
> (I didn't tag the patch for stable@ for a reason).
> 
> > > Or am I missing something?
> > 
> > Thanks for reporting.
> > 
> > If Sean and/or Paolo agree, we can revoke the CVE for you.
> 
> Please do.

No problem.  All done for you:

https://lore.kernel.org/all/20240311161318.1290374-2-lee@kernel.org/

Thanks again for the report.

-- 
Lee Jones [李琼斯]