CVE-2023-46835
Vulnerability from cvelistv5
Published
2024-01-05 16:34
Modified
2024-09-04 19:39
Severity ?
Summary
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.
References
security@xen.orghttps://xenbits.xenproject.org/xsa/advisory-445.htmlPatch, Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108https://xenbits.xenproject.org/xsa/advisory-445.htmlPatch, Vendor Advisory
Impacted products
Vendor Product Version
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        "providerMetadata": {
          "dateUpdated": "2024-08-02T20:53:21.879Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
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            "tags": [
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            "url": "https://xenbits.xenproject.org/xsa/advisory-445.html"
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        "title": "CVE Program Container"
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        "metrics": [
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              "content": {
                "id": "CVE-2023-46835",
                "options": [
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                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
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                    "Technical Impact": "partial"
                  }
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                "role": "CISA Coordinator",
                "timestamp": "2024-04-12T04:00:28.791183Z",
                "version": "2.0.3"
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          "dateUpdated": "2024-09-04T19:39:59.020Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unknown",
          "product": "Xen",
          "vendor": "Xen",
          "versions": [
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      "configurations": [
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        }
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      "credits": [
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          "type": "finder",
          "value": "This issue was discovered by Roger Pau Monn\u00e9 of XenServer.\n"
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          "lang": "en",
          "value": "The current setup of the quarantine page tables assumes that the\nquarantine domain (dom_io) has been initialized with an address width\nof DEFAULT_DOMAIN_ADDRESS_WIDTH (48) and hence 4 page table levels.\n\nHowever dom_io being a PV domain gets the AMD-Vi IOMMU page tables\nlevels based on the maximum (hot pluggable) RAM address, and hence on\nsystems with no RAM above the 512GB mark only 3 page-table levels are\nconfigured in the IOMMU.\n\nOn systems without RAM above the 512GB boundary\namd_iommu_quarantine_init() will setup page tables for the scratch\npage with 4 levels, while the IOMMU will be configured to use 3 levels\nonly, resulting in the last page table directory (PDE) effectively\nbecoming a page table entry (PTE), and hence a device in quarantine\nmode gaining write access to the page destined to be a PDE.\n\nDue to this page table level mismatch, the sink page the device gets\nread/write access to is no longer cleared between device assignment,\npossibly leading to data leaks.\n"
        }
      ],
      "impacts": [
        {
          "descriptions": [
            {
              "lang": "en",
              "value": "A device in quarantine mode can access data from previous quarantine\npage table usages, possibly leaking data used by previous domains that\nalso had the device assigned.\n"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2024-01-05T16:34:49.531Z",
        "orgId": "23aa2041-22e1-471f-9209-9b7396fa234f",
        "shortName": "XEN"
      },
      "references": [
        {
          "url": "https://xenbits.xenproject.org/xsa/advisory-445.html"
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      ],
      "title": "x86/AMD: mismatch in IOMMU quarantine page table levels",
      "workarounds": [
        {
          "lang": "en",
          "value": "Not passing through physical devices to guests will avoid the\nvulnerability.\n\nNot using quarantine scratch-page mode will avoid the vulnerability,\nbut could result in other issues.\n"
        }
      ]
    }
  },
  "cveMetadata": {
    "assignerOrgId": "23aa2041-22e1-471f-9209-9b7396fa234f",
    "assignerShortName": "XEN",
    "cveId": "CVE-2023-46835",
    "datePublished": "2024-01-05T16:34:49.531Z",
    "dateReserved": "2023-10-27T07:55:35.331Z",
    "dateUpdated": "2024-09-04T19:39:59.020Z",
    "state": "PUBLISHED"
  },
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