linux-kernel - Re: CVE-2025-38026: x86/sev: Do not touch VMSA pages during SNP guest memory kdump

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Message-ID: <2025061809-cattishly-refutable-956e@gregkh>
Date: Wed, 18 Jun 2025 13:21:21 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Juergen Gross <jgross@...e.com>
Cc: cve@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: CVE-2025-38026: x86/sev: Do not touch VMSA pages during SNP
 guest memory kdump

On Wed, Jun 18, 2025 at 11:57:22AM +0200, Juergen Gross wrote:
> On 18.06.25 11:29, Greg Kroah-Hartman wrote:
> > From: Greg Kroah-Hartman <gregkh@...nel.org>
> > 
> > Description
> > ===========
> > 
> > In the Linux kernel, the following vulnerability has been resolved:
> > 
> > x86/sev: Do not touch VMSA pages during SNP guest memory kdump
> > 
> > When kdump is running makedumpfile to generate vmcore and dump SNP guest
> > memory it touches the VMSA page of the vCPU executing kdump.
> > 
> > It then results in unrecoverable #NPF/RMP faults as the VMSA page is
> > marked busy/in-use when the vCPU is running and subsequently a causes
> > guest softlockup/hang.
> > 
> > Additionally, other APs may be halted in guest mode and their VMSA pages
> > are marked busy and touching these VMSA pages during guest memory dump
> > will also cause #NPF.
> > 
> > Issue AP_DESTROY GHCB calls on other APs to ensure they are kicked out
> > of guest mode and then clear the VMSA bit on their VMSA pages.
> > 
> > If the vCPU running kdump is an AP, mark it's VMSA page as offline to
> > ensure that makedumpfile excludes that page while dumping guest memory.
> > 
> > The Linux kernel CVE team has assigned CVE-2025-38026 to this issue.
> 
> I don't see how this issue could be triggered by an unprivileged user.
> I think this CVE should be revoked.

Now rejected, thanks for the review.

greg k-h