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CVE-2025-38455 — KVM: SVM: Reject SEV{-ES} intra host migration if vCPU creation is in-flight

Affected: Linux

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

KVM: SVM: Reject SEV{-ES} intra host migration if vCPU creation is in-flight

Reject migration of SEV{-ES} state if either the source or destination VM is actively creating a vCPU, i.e. if kvm_vm_ioctl_create_vcpu() is in the section between incrementing created_vcpus and online_vcpus. The bulk of vCPU creation runs _outside_ of kvm->lock to allow creating multiple vCPUs in parallel, and so sev_info.es_active can get toggled from false=>true in the destination VM after (or during) svm_vcpu_create(), resulting in an SEV{-ES} VM effectively having a non-SEV{-ES} vCPU.

The issue manifests most visibly as a crash when trying to free a vCPU's NULL VMSA page in an SEV-ES VM, but any number of things can go wrong.

BUG: unable to handle page fault for address: ffffebde00000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops: 0000 [#1] SMP KASAN NOPTI CPU: 227 UID: 0 PID: 64063 Comm: syz.5.60023 Tainted: G U O 6.15.0-smp-DEV #2 NONE Tainted: [U]=USER, [O]=OOT_MODULE Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 12.52.0-0 10/28/2024 RIP: 0010:constant_test_bit arch/x86/include/asm/bitops.h:206 [inline] RIP: 0010:arch_test_bit arch/x86/include/asm/bitops.h:238 [inline] RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline] RIP: 0010:PageHead include/linux/page-flags.h:86…

USN-7879-1 — linux, linux-aws, linux-gcp, linux-hwe-6.14, linux-oracle, linux-realtime vulnerabilities

Affected: Ubuntu:24.04:LTS: linux-hwe-6.14

It was discovered that improper initialization of CPU cache memory could allow a local attacker with hypervisor access to overwrite SEV-SNP guest memory resulting in loss of data integrity. (CVE-2024-36331)

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - ARM64 architecture; - PowerPC architecture; - S390 architecture; - x86 architecture; - Network block device driver; - Character device driver; - Clock framework and drivers; - Data acquisition framework and drivers; - Hardware crypto device drivers; - Device frequency scaling framework; - DMA engine subsystem; - EDAC drivers; - GPU drivers; - HID subsystem; - Hardware monitoring drivers; - I2C subsystem; - IIO subsystem; - IIO ADC drivers; - InfiniBand drivers; - Input Device core drivers; - Multiple devices driver; - Media drivers; - Network drivers; - Mellanox network drivers; - PCI subsystem; - PHY drivers; - Pin controllers subsystem; - x86 platform drivers; - Power supply drivers; - Powercap sysfs driver; - Voltage and Current Regulator drivers; - S/390 drivers; - ASPEED SoC drivers; - SPI subsystem; - small TFT LCD display modules; - Media staging drivers; - USB Gadget drivers; - vDPA drivers; - VFIO drivers; - Framebuffer layer; - Xen hypervisor drivers; - BTRFS file system; - Ceph distributed file sy…