CVE-2019-19577

xen: vulnerability in dynamic height handling for AMD IOMMU pagetables (XSA-311 v2)

Published Dec 11, 2019 CVSS 3.1 · 7.2 High EPSS < 1% KEV · Not listed
Description
An issue was discovered in Xen through 4.12.x allowing x86 AMD HVM guest OS users to cause a denial of service or possibly gain privileges by triggering data-structure access during pagetable-height updates. When running on AMD systems with an IOMMU, Xen attempted to dynamically adapt the number of levels of pagetables (the pagetable height) in the IOMMU according to the guest's address space size. The code to select and update the height had several bugs. Notably, the update was done without taking a lock which is necessary for safe operation. A malicious guest administrator can cause Xen to access data structures while they are being modified, causing Xen to crash. Privilege escalation is thought to be very difficult but cannot be ruled out. Additionally, there is a potential memory leak of 4kb per guest boot, under memory pressure. Only Xen on AMD CPUs is vulnerable. Xen running on Intel CPUs is not vulnerable. ARM systems are not vulnerable. Only systems where guests are given direct access to physical devices are vulnerable. Systems which do not use PCI pass-through are not vulnerable. Only HVM guests can exploit the vulnerability. PV and PVH guests cannot. All versions of Xen with IOMMU support are vulnerable.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DSA Debian DSA DSA-4602-1 xen security update
EUVD EUVD EUVD-2019-9194 An issue was discovered in Xen through 4.12.x allowing x86 AMD HVM guest OS users to cause a denial of service or possibly gain privileges by triggering data-structure access during pagetable-height updates. When running on AMD systems with an IOMMU, Xen attempted to dynamically adapt the number of levels of pagetables (the pagetable height) in the IOMMU according to the guest's address space size. The code to select and update the height had several bugs. Notably, the update was done without taking a lock which is necessary for safe operation. A malicious guest administrator can cause Xen to access data structures while they are being modified, causing Xen to crash. Privilege escalation is thought to be very difficult but cannot be ruled out. Additionally, there is a potential memory leak of 4kb per guest boot, under memory pressure. Only Xen on AMD CPUs is vulnerable. Xen running on Intel CPUs is not vulnerable. ARM systems are not vulnerable. Only systems where guests are given direct access to physical devices are vulnerable. Systems which do not use PCI pass-through are not vulnerable. Only HVM guests can exploit the vulnerability. PV and PVH guests cannot. All versions of Xen with IOMMU support are vulnerable.
History

No history.

Weaknesses

Sources

Status
PUBLISHED
Assigner
mitre
Published
Updated
Aug 5, 2024, 2:16 AM
Reserved
Dec 4, 2019, 12:00 AM
Status
Modified
Published
Dec 11, 2019, 6:16 PM
Modified
Jun 17, 2026, 2:26 AM
Severity
Moderate
Public date
Dec 11, 2019, 12:00 AM