x86/AMD: mismatch in IOMMU quarantine page table levels

CVE-2023-46835

What is CVE-2023-46835?

A critical issue arises within the Xen Hypervisor where the initialization of quarantine page tables does not align with the actual IOMMU configuration. The mismatch occurs because the quarantine domain, assumed to have a default address width, may only support a maximum of three page table levels on systems with less than 512GB of RAM. This leads to scenarios where a device in quarantine mode could potentially gain unauthorized write access, compromising sensitive information that should remain isolated. The implications of this vulnerability suggest a significant risk of data leaks through improper handling of page tables during device assignment. Remediation is essential to ensure the integrity and confidentiality of data within the hypervisor environment.

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