OpenShift Sandboxed Containersの脆弱性、悪意あるホストから機密計算ゲストのメモリ内容が漏えいするおそれ

A flaw was found in the interaction between systemd-gpt-auto-generator and
confidential computing guest VM images in OpenShift Sandboxed Containers
(confidential peer pods). systemd-gpt-auto-generator automatically discovers
and mounts GPT partitions by type GUID at boot with no user confirmation. In
the confidential computing threat model, where the host/hypervisor is the
adversary, a malicious host can inject partitions into the guest's virtual
disk. Most critically, injecting a swap partition causes the guest kernel to
page out TEE-encrypted memory to a host-controlled block device, breaking the
confidentiality guarantee of the hardware TEE (AMD SEV-SNP, Intel TDX).

The PodVM images use a GPT-partitioned disk with dm-verity on the root
partition. However, the roothash= kernel parameter only disables root
auto-discovery — non-root partitions (swap, /home, /var, /srv, /var/tmp) are
still auto-discovered and mounted. The generator is shipped unmasked in the
RHEL systemd-udev subpackage, and no kernel command line parameter in the
measured UKI addon disables it. Additionally, the PodVM measurement script
captures PCRs 3, 9, 11, and 12, but not PCR 5 (GPT partition table), so
partition table modifications are not detected by remote attestation.