CVE-2021-28702

PCI devices with RMRRs not deassigned correctly Certain PCI devices in a system might be assigned Reserved Memory Regions (specified via Reserved Memory Region Reporting, “RMRR”). These are typically used for platform tasks such as legacy USB emulation. If such a device is passed through to a guest, then on guest shutdown the device is not properly deassigned. The IOMMU configuration for these devices which are not properly deassigned ends up pointing to a freed data structure, including the IO Pagetables. Subsequent DMA or interrupts from the device will have unpredictable behaviour, ranging from IOMMU faults to memory corruption.

Summary:

PCI devices with RMRRs not deassigned correctly Certain PCI devices in a system might be assigned Reserved Memory Regions (specified via Reserved Memory Region Reporting, “RMRR”). These are typically used for platform tasks such as legacy USB emulation. If such a device is passed through to a guest, then on guest shutdown the device is not properly deassigned. The IOMMU configuration for these devices which are not properly deassigned ends up pointing to a freed data structure, including the IO Pagetables. Subsequent DMA or interrupts from the device will have unpredictable behaviour, ranging from IOMMU faults to memory corruption.

Reference Links(if available):

  • https://xenbits.xenproject.org/xsa/advisory-386.txt
  • http://www.openwall.com/lists/oss-security/2021/10/07/2
  • https://lists.fedoraproject.org/archives/list/[email protected]/message/FDPRMOBBLS74ONYP3IXZZXSTLKR7GRQB/
  • https://lists.fedoraproject.org/archives/list/[email protected]/message/TRAWV6PO2KUGVZTESERECOBUBZ6X45I7/
  • https://lists.fedoraproject.org/archives/list/[email protected]/message/2OIHEJ3R3EH5DYI2I5UMD2ULJ2ELA3EX/
  • CVSS Score (if available)

    v2: / MEDIUMAV:L/AC:L/Au:N/C:P/I:P/A:P

    v3: / HIGHCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

    Links to Exploits(if available)