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Message-Id: <5ecf18f8-e8e9-431d-bb59-4631a598574e@vates.tech>
Date: Thu, 27 Feb 2025 15:33:18 +0000
From: "Teddy Astie" <teddy.astie@...es.tech>
To: "Xen.org security team" <security@....org>, xen-announce@...ts.xen.org, xen-devel@...ts.xen.org, xen-users@...ts.xen.org, oss-security@...ts.openwall.com
Cc: "Xen.org security team" <security-team-members@....org>
Subject: Re: Xen Security Advisory 467 v1 (CVE-2025-1713) - deadlock potential with VT-d and legacy PCI device pass-through
Hello,
Le 27/02/2025 à 13:57, Xen.org security team a écrit :
> Xen Security Advisory CVE-2025-1713 / XSA-467
>
> deadlock potential with VT-d and legacy PCI device pass-through
>
> ISSUE DESCRIPTION
> =================
>
> When setting up interrupt remapping for legacy PCI(-X) devices,
> including PCI(-X) bridges, a lookup of the upstream bridge is required.
> This lookup, itself involving acquiring of a lock, is done in a context
> where acquiring that lock is unsafe. This can lead to a deadlock.
>
> IMPACT
> ======
>
> The passing through of certain kinds of devices to an unprivileged guest
> can result in a Denial of Service (DoS) affecting the entire host.
>
> Note: Normal usage of such devices by a privileged domain can also
> trigger the issue. In such a scenario, the deadlock is not
> considered a security issue, but just a plain bug.
>
> VULNERABLE SYSTEMS
> ==================
>
> Xen versions 4.0 and later are affected. Xen versions 3.4 and earlier
> are not directly affected, but had other issues.
>
> Systems with Intel IOMMU hardware (VT-d) are affected. Systems using
> AMD or non-x86 hardware are not affected.
>
> Only systems where certain kinds of devices are passed through to an
> unprivileged guest are vulnerable.
>
> MITIGATION
> ==========
>
> Avoiding the passing through of the affected device types will avoid
> the vulnerability.
>
Is disabling interrupt remapping another way of mitigating this
vulnerability (e.g iommu=no-intremap) ?
> RESOLUTION
> ==========
>
> Applying the attached patch resolves this issue.
>
> Note that patches for released versions are generally prepared to
> apply to the stable branches, and may not apply cleanly to the most
> recent release tarball. Downstreams are encouraged to update to the
> tip of the stable branch before applying these patches.
>
> xsa467.patch xen-unstable - Xen 4.17.x
>
> $ sha256sum xsa467*
> 2fffaa8892b3daecd698b4af95701045874a76edc2e18c8d2abbec85a39aa05c xsa467.patch
> $
>
> NOTE REGARDING LACK OF EMBARGO
> ==============================
>
> The issue was reported initially on a public bug tracker and discussed in
> public before it was realized that there was a security aspect.
Teddy
Teddy Astie | Vates XCP-ng Developer
XCP-ng & Xen Orchestra - Vates solutions
web: https://vates.tech
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