Google Cloud warns of three AMD Turin CPU flaws that can leak data between processes in VMs

Customers must install OS fixes and fully stop and start affected VMs, and host operators should expect BIOS updates from server makers through December.

Google Cloud has warned customers that three side-channel flaws in AMD's Turin EPYC processors could let code on the same core infer data from other processes or the kernel inside a VM. Google says it has already mitigated attacks between VMs and between VMs and the host, and that VM owners must install their OS vendor's fix and then stop and start the VM, since a guest reboot is not enough. Separately, two attacks published this week let a malicious host read data inside AMD SEV-SNP virtual machines: Mior, found by an ETH Zurich team, corrupts the Reverse Map Table during start-up and can also forge attestation reports, while Skyfall, from ETH Zurich and Google, leaks saved register values and a disk-encryption key through Transient Scheduler Attacks. AMD dated its SEV firmware for Mior on August 12, with platform firmware for Skyfall due in November and for Mior in December, so operators of SEV-SNP hosts should plan for BIOS updates from their server makers.