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CVE-2023-46835— x86/AMD: mismatch in IOMMU quarantine page table levels

Quick assessment

Affected
Xen Xen
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Xen是英国剑桥（Cambridge）大学的一款开源的虚拟机监视器产品。该产品能够使不同和不兼容的操作系统运行在同一台计算机上，并支持在运行时进行迁移，保证正常运行并且避免宕机。 Xen存在安全漏洞，该漏洞源于IOMMU隔离页表级别不匹配。

AI Predicted 6.5 Difficulty: Hard EPSS 0.28% · P19

Possible ATT&CK Techniques 1 AI

T1115 · Clipboard Data
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I. Basic Information for CVE-2023-46835

Vulnerability Information
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Vulnerability Title
x86/AMD: mismatch in IOMMU quarantine page table levels
Source: CVE Program / CVE List V5
Vulnerability Description
The current setup of the quarantine page tables assumes that the quarantine domain (dom_io) has been initialized with an address width of DEFAULT_DOMAIN_ADDRESS_WIDTH (48) and hence 4 page table levels. However dom_io being a PV domain gets the AMD-Vi IOMMU page tables levels based on the maximum (hot pluggable) RAM address, and hence on systems with no RAM above the 512GB mark only 3 page-table levels are configured in the IOMMU. On systems without RAM above the 512GB boundary amd_iommu_quarantine_init() will setup page tables for the scratch page with 4 levels, while the IOMMU will be configured to use 3 levels only, resulting in the last page table directory (PDE) effectively becoming a page table entry (PTE), and hence a device in quarantine mode gaining write access to the page destined to be a PDE. Due to this page table level mismatch, the sink page the device gets read/write access to is no longer cleared between device assignment, possibly leading to data leaks.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Xen 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Xen是英国剑桥（Cambridge）大学的一款开源的虚拟机监视器产品。该产品能够使不同和不兼容的操作系统运行在同一台计算机上，并支持在运行时进行迁移，保证正常运行并且避免宕机。 Xen存在安全漏洞，该漏洞源于IOMMU隔离页表级别不匹配。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Xen Xen consult Xen advisory XSA-445 -

II. Public POCs for CVE-2023-46835

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III. Intelligence Information for CVE-2023-46835

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Other References for CVE-2023-46835 (1)

Same Patch Batch · Xen · 2024-01-05 · 10 CVEs total

CVE-2023-46837 arm32: The cache may not be properly cleaned/invalidated (take two)
CVE-2023-46836 x86: BTC/SRSO fixes not fully effective
CVE-2023-34327 x86/AMD: Debug Mask handling
CVE-2023-34328 x86/AMD: Debug Mask handling
CVE-2023-34325 Multiple vulnerabilities in libfsimage disk handling
CVE-2023-34326 x86/AMD: missing IOMMU TLB flushing
CVE-2023-34323 xenstored: A transaction conflict can crash C Xenstored
CVE-2023-34322 top-level shadow reference dropped too early for 64-bit PV guests
CVE-2023-34321 arm32: The cache may not be properly cleaned/invalidated

IV. Related Vulnerabilities

Same product: Xen
Same vendor: Xen

V. Comments for CVE-2023-46835

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