From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E99391519BE for ; Sun, 2 Mar 2025 14:27:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740925624; cv=none; b=imOKZLJI2sZyAOo2mdFHm+gbG2A6EGTdTaVZui6Q3sZ0UKxCxf6LRQaZuESAnzKnTCbK4Zkmqu+jR26eRCUw7n6GGbuqg9GuxKfkxhv2+9Zxyigv/Nd1wqW6XXmAV3H8oIN9K135xePjcRXR5BsXQMdz0jxjJGhtXUpBxujeKgM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740925624; c=relaxed/simple; bh=aKaIxUY0VRW52Ui8iC6HgHNpx18yvJM6J9k61Z/ZbQQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=o0Fq6EUu8OqhP1Xtg4bR6JAHnukBkK0h0RvaLJogJi/oZWeElMGvC8QcOQ9Tn1ejVBeThbquNW6hCNfy6/Zqu0OZpepGB6qXGzdXYG6sufRqnIvJfPhxi6b40SKiKFlL1ESF1HB7D1F6pxLsDN+aTeZElIDHBw8cf3yp3qiRSro= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=H8ymg5Q8; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="H8ymg5Q8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 20AF3C4CED6; Sun, 2 Mar 2025 14:27:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1740925623; bh=aKaIxUY0VRW52Ui8iC6HgHNpx18yvJM6J9k61Z/ZbQQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=H8ymg5Q8bIdFt93m2U5HK15vHs5s9VHwJLvssNBmSdTgto4kT8YyHKGg5EfGXcC20 O5lYoo62RjrJMbBbD7UJrfoqoV6m2+6r7KlF1Z9YU2ScjF+mtlB7YPDAJuQXqr680c nump01TzP46udHSDNQMEwEbRWRYsh6thp384BZ54= Date: Sun, 2 Mar 2025 15:25:50 +0100 From: Greg KH To: Juergen Gross Cc: cve@kernel.org, linux-kernel@vger.kernel.org Subject: Re: CVE-2025-21818: x86/xen: fix xen_hypercall_hvm() to not clobber %rbx Message-ID: <2025030236-item-coral-d4b3@gregkh> References: <2025022710-CVE-2025-21818-27ee@gregkh> 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: On Fri, Feb 28, 2025 at 08:28:48AM +0100, Juergen Gross wrote: > On 27.02.25 21:03, Greg Kroah-Hartman wrote: > > Description > > =========== > > > > In the Linux kernel, the following vulnerability has been resolved: > > > > x86/xen: fix xen_hypercall_hvm() to not clobber %rbx > > > > xen_hypercall_hvm(), which is used when running as a Xen PVH guest at > > most only once during early boot, is clobbering %rbx. Depending on > > whether the caller relies on %rbx to be preserved across the call or > > not, this clobbering might result in an early crash of the system. > > > > This can be avoided by using an already saved register instead of %rbx. > > > > The Linux kernel CVE team has assigned CVE-2025-21818 to this issue. > > Please revoke this CVE. > > There is no way an unprivileged user can trigger this issue at will. > The issue is guest local and will either happen very early at boot or > it won't happen at all. > > So no security issue. Now rejected, thanks for the review. greg k-h