linux-kernel - Re: CVE-2024-35802: x86/sev: Fix position dependent variable references in startup code

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Date: Tue, 28 May 2024 21:08:22 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Michal Hocko <mhocko@...e.com>
Cc: Nikolay Borisov <nik.borisov@...e.com>, cve@...nel.org,
	linux-kernel@...r.kernel.org, linux-cve-announce@...r.kernel.org
Subject: Re: CVE-2024-35802: x86/sev: Fix position dependent variable
 references in startup code

On Tue, May 28, 2024 at 10:51:52AM +0200, Michal Hocko wrote:
> On Thu 23-05-24 14:14:57, Nikolay Borisov wrote:
> [...]
> > I'd like to dispute this CVE since it doesn't constitute a security related
> > bug. Sure, it might crash a SEV guest during boot but it doesn't constitute
> > a security issue per-se.
> 
> Let me add analysis by Joerg here:
> : This is not a security issue. The patch works around clangs compiler behavior
> : where it inserts absolute references to kernel addresses. This breaks kernel
> : boot because at the time this code runs the kernel still runs direct-mapped and
> : needs to rely on RIP-relative addressing only.
> : 
> : Any breakage there would be detected at early boot of the kernel by a fatal
> : crash, which can not be exploited. Also, our kernels are not compiled with
> : clang, so from that perspective this is also not an issue for us either.
> 
> So this is a functional fix for clang builds.

Thanks for the review, now rejected.

greg k-h