CVE-2021-47035: iommu/vt-d: Remove WO permissions on second-level paging entries
In the Linux kernel, the following vulnerability has been resolved:
iommu/vt-d: Remove WO permissions on second-level paging entries
When the first level page table is used for IOVA translation, it only supports Read-Only and Read-Write permissions. The Write-Only permission is not supported as the PRESENT bit (implying Read permission) should always set. When using second level, we still give separate permissions that allows WriteOnly which seems inconsistent and awkward. We want to have consistent behavior. After moving to 1st level, we don't want things to work sometimes, and break if we use 2nd level for the same mappings. Hence remove this configuration.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Remove
Remove
iommu/vt-d: Remove WO permissions on second-level paging entriesfrom your environment.Remove Write-Only (WO) permissions on second-level paging entries to make IOVA translation behave consistently when the first-level page table is used versus when second-level paging is used.
Event History
Frequently Asked Questions
What is the severity of CVE-2021-47035?
CVE-2021-47035 has been assigned a medium severity level due to its impact on system security.
How do I fix CVE-2021-47035?
To fix CVE-2021-47035, update your Linux kernel to version 5.10.37 or later, or to 5.11.21 or later, or to 5.12.4 or later.
What systems are affected by CVE-2021-47035?
CVE-2021-47035 affects versions of the Linux kernel from 5.6 up to 5.10.37, 5.11 up to 5.11.21, and 5.12 up to 5.12.4.
What is the nature of the vulnerability in CVE-2021-47035?
CVE-2021-47035 involves improper permission handling in second-level paging entries in the IOMMU subsystem of the Linux kernel.
Is there a workaround for CVE-2021-47035 if I can't update?
There are no known workarounds for CVE-2021-47035, so updating the Linux kernel is the recommended course of action.