UBUNTU-CVE-2021-29657

Description

arch/x86/kvm/svm/nested.c in the Linux kernel before 5.11.12 has a use-after-free in which an AMD KVM guest can bypass access control on host OS MSRs when there are nested guests, aka CID-a58d9166a756. This occurs because of a TOCTOU race condition associated with a VMCB12 double fetch in nested_svm_vmrun.

CVSS Metrics

• v3.1•HIGH•Score: 7.4CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Systems

• ubuntu•linux-aws-5.0

  all

• ubuntu•linux-aws-5.3

  all

• ubuntu•linux-azure

  all

• ubuntu•linux-azure-5.3

  all

• ubuntu•linux-azure-edge

  all

• ubuntu•linux-gcp

  all

• ubuntu•linux-gcp-5.3

  all

• ubuntu•linux-gcp-edge

  all

• ubuntu•linux-gke-4.15

  all

• ubuntu•linux-hwe

  all

• ubuntu•linux-hwe-edge

  all | all

• ubuntu•linux-oem

  all

• ubuntu•linux-oem-5.10

  < 5.10.0-1025.26

• ubuntu•linux-oracle-5.0

  all

• ubuntu•linux-oracle-5.3

  all

• ubuntu•linux-raspi2

  all

• ubuntu•linux-riscv

  all

References (4)

• https://ubuntu.com/security/CVE-2021-29657
• https://git.kernel.org/linus/a58d9166a756a0f4a6618e4f593232593d6df134
• https://ubuntu.com/security/notices/USN-4948-1
• https://www.cve.org/CVERecord?id=CVE-2021-29657