A flaw was found in the KVM's AMD code for supporting SVM nested virtualization. The flaw occurs when processing the VMCB (virtual machine control block) provided by the L1 guest to spawn/handle a nested guest (L2). Due to improper validation of the "virt_ext" field, this issue could allow a malicious L1 to disable both VMLOAD/VMSAVE intercepts and VLS (Virtual VMLOAD/VMSAVE) for the L2 guest. As a result, the L2 guest would be allowed to read/write physical pages of the host, resulting in a crash of the entire system, leak of sensitive data or potential guest-to-host escape.

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-2785-1 linux-4.19 security update
Debian DSA Debian DSA DSA-4978-1 linux security update
EUVD EUVD EUVD-2021-26951 A flaw was found in the KVM's AMD code for supporting SVM nested virtualization. The flaw occurs when processing the VMCB (virtual machine control block) provided by the L1 guest to spawn/handle a nested guest (L2). Due to improper validation of the "virt_ext" field, this issue could allow a malicious L1 to disable both VMLOAD/VMSAVE intercepts and VLS (Virtual VMLOAD/VMSAVE) for the L2 guest. As a result, the L2 guest would be allowed to read/write physical pages of the host, resulting in a crash of the entire system, leak of sensitive data or potential guest-to-host escape.
Ubuntu USN Ubuntu USN USN-5070-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-5071-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-5071-2 Linux kernel (HWE) vulnerabilities
Ubuntu USN Ubuntu USN USN-5072-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-5073-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-5073-2 Linux kernel (GCP) vulnerabilities
Ubuntu USN Ubuntu USN USN-5082-1 Linux kernel (OEM) vulnerabilities
Fixes

Solution

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cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2024-08-03T17:01:07.792Z

Reserved: 2021-07-21T00:00:00

Link: CVE-2021-3656

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Modified

Published: 2022-03-04T19:15:08.677

Modified: 2024-11-21T06:22:05.187

Link: CVE-2021-3656

cve-icon Redhat

Severity : Moderate

Publid Date: 2021-08-16T12:00:00Z

Links: CVE-2021-3656 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses