Vulnerability · Published Jan 5, 2024 · Assigned by XEN
CVE-2023-46835x86/AMD: mismatch in IOMMU quarantine page table levels
Medium 5.5
In plain English
A medium-severity out-of-bounds write in Xen from Xen. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 21% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | xen | 4.17.2-r4 | ALPINE-CVE-2023-46835 |
| Alpine:v3.21 | xen | 4.17.2-r4 | ALPINE-CVE-2023-46835 |
| Alpine:v3.22 | xen | 4.17.2-r4 | ALPINE-CVE-2023-46835 |
| Alpine:v3.23 | xen | 4.17.2-r4 | ALPINE-CVE-2023-46835 |
| Alpine:v3.24 | xen | 4.17.2-r4 | ALPINE-CVE-2023-46835 |
| Debian:12 | xen | 4.17.2+76-ge1f9cb16e2-1~deb12u1 | DEBIAN-CVE-2023-46835 |
| Debian:13 | xen | 4.17.2+76-ge1f9cb16e2-1 | DEBIAN-CVE-2023-46835 |
| Debian:14 | xen | 4.17.2+76-ge1f9cb16e2-1 | DEBIAN-CVE-2023-46835 |
| Ubuntu:22.04:LTS | xen | no fix listed | UBUNTU-CVE-2023-46835 |
| Ubuntu:24.04:LTS | xen | no fix listed | UBUNTU-CVE-2023-46835 |
| Ubuntu:25.10 | xen | no fix listed | UBUNTU-CVE-2023-46835 |
| Ubuntu:26.04:LTS | xen | no fix listed | UBUNTU-CVE-2023-46835 |
| Ubuntu:26.10 | xen | no fix listed | UBUNTU-CVE-2023-46835 |
Affected products (as reported)
Weakness: CWE-787 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N