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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Xen | Xen | All versions |
Related Weaknesses (CWE)
References
- https://xenbits.xenproject.org/xsa/advisory-445.htmlPatchVendor Advisory
- http://xenbits.xen.org/xsa/advisory-445.html
- https://xenbits.xenproject.org/xsa/advisory-445.htmlPatchVendor Advisory
FAQ
What is CVE-2023-46835?
CVE-2023-46835 is a vulnerability with a CVSS score of 5.5 (MEDIUM). 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 level...
How severe is CVE-2023-46835?
CVE-2023-46835 has been rated MEDIUM with a CVSS base score of 5.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2023-46835?
Check the references section above for vendor advisories and patch information. Affected products include: Xen Xen.