In the Linux kernel, the following vulnerability has been resolved: crypto: ccp - Do not initialize SNP for SEV ioctls Sashiko notes: > if SEV initialization fails and KVM is actively running normal VMs, could a > userspace process trigger this code path via /dev/sev ioctls (e.g., > SEV_PDH_GEN) and zero out MSR_VM_HSAVE_PA globally? Would the next VMRUN > execution for an active VM trigger a general protection fault and crash the > host? sev_move_to_init_state() is called for ioctls requiring only SEV firmware: SEV_PEK_GEN, SEV_PDH_GEN, SEV_PEK_CSR, SEV_PEK_CERT_IMPORT, and SEV_PDH_CERT_EXPORT. After the firmware command, it does SEV_SHUTDOWN on the SEV firmware. Since these commands do not require SNP to be initialized, skip it by calling __sev_platform_init_locked() which only initializes the SEV firmware. This way SNP is not Initialized at all, and HSAVE_PA is not cleared. The previous code saved any SEV initialization firmware error to init_args.error and then threw it away and...

A flaw was found in the Linux kernel's crypto: ccp component. A local user, by triggering specific SEV (Secure Encrypted Virtualization) input/output control (ioctl) operations when SEV initialization fails and Kernel-based Virtual Machine (KVM) is actively running virtual machines, could cause the system to zero out a critical hardware register. This could lead to a general protection fault, resulting in a denial of service (DoS) by crashing the host system.

In the Linux kernel, the following vulnerability has been resolved: crypto: ccp - Do not initialize SNP for SEV ioctls Sashiko notes: > if SEV initialization fails and KVM is actively running normal VMs, could a > userspace process trigger this code path via /dev/sev ioctls (e.g., > SEV_PDH_GEN) and zero out MSR_VM_HSAVE_PA globally? Would the next VMRUN > execution for an active VM trigger a general protection fault and crash the > host? sev_move_to_init_state() is called for ioctls requiring only SEV firmware: SEV_PEK_GEN, SEV_PDH_GEN, SEV_PEK_CSR, SEV_PEK_CERT_IMPORT, and SEV_PDH_CERT_EXPORT. After the firmware command, it does SEV_SHUTDOWN on the SEV firmware. Since these commands do not require SNP to be initialized, skip it by calling __sev_platform_init_locked() which only initializes the SEV firmware. This way SNP is not Initialized at all, and HSAVE_PA is not cleared. The previous code saved any SEV initialization firmware error to init_args.error and then threw it away a

In the Linux kernel, the following vulnerability has been resolved: c ...

In the Linux kernel, the following vulnerability has been resolved: crypto: ccp - Do not initialize SNP for SEV ioctls Sashiko notes: > if SEV initialization fails and KVM is actively running normal VMs, could a > userspace process trigger this code path via /dev/sev ioctls (e.g., > SEV_PDH_GEN) and zero out MSR_VM_HSAVE_PA globally? Would the next VMRUN > execution for an active VM trigger a general protection fault and crash the > host? sev_move_to_init_state() is called for ioctls requiring only SEV firmware: SEV_PEK_GEN, SEV_PDH_GEN, SEV_PEK_CSR, SEV_PEK_CERT_IMPORT, and SEV_PDH_CERT_EXPORT. After the firmware command, it does SEV_SHUTDOWN on the SEV firmware. Since these commands do not require SNP to be initialized, skip it by calling __sev_platform_init_locked() which only initializes the SEV firmware. This way SNP is not Initialized at all, and HSAVE_PA is not cleared. The previous code saved any SEV initialization firmware error to init_args.error and then threw it awa...