CVE-2024-40953

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() Use {READ,WRITE}_ONCE() to access kvm->last_boosted_vcpu to ensure the loads and stores are atomic. In the extremely unlikely scenario the compiler tears the stores, it's theoretically possible for KVM to attempt to get a vCPU using an out-of-bounds index, e.g. if the write is split into multiple 8-bit stores, and is paired with a 32-bit load on a VM with 257 vCPUs: CPU0 CPU1 last_boosted_vcpu = 0xff; (last_boosted_vcpu = 0x100) last_boosted_vcpu[15:8] = 0x01; i = (last_boosted_vcpu = 0x1ff) last_boosted_vcpu[7:0] = 0x00; vcpu = kvm->vcpu_array[0x1ff]; As detected by KCSAN: BUG: KCSAN: data-race in kvm_vcpu_on_spin [kvm] / kvm_vcpu_on_spin [kvm] write to 0xffffc90025a92344 of 4 bytes by task 4340 on cpu 16: kvm_vcpu_on_spin (arch/x86/kvm/../../../virt/kvm/kvm_main.c:4112) kvm handle_pause (arch/x86/kvm/vmx/vmx.c:5929) kvm_intel vmx_handle_exit (arch/x86/kvm/vmx/vmx.c:? arch/x86/kvm/vmx/vmx.c:6606) kvm_intel vcpu_run (arch/x86/kvm/x86.c:11107 arch/x86/kvm/x86.c:11211) kvm kvm_arch_vcpu_ioctl_run (arch/x86/kvm/x86.c:?) kvm kvm_vcpu_ioctl (arch/x86/kvm/../../../virt/kvm/kvm_main.c:?) kvm __se_sys_ioctl (fs/ioctl.c:52 fs/ioctl.c:904 fs/ioctl.c:890) __x64_sys_ioctl (fs/ioctl.c:890) x64_sys_call (arch/x86/entry/syscall_64.c:33) do_syscall_64 (arch/x86/entry/common.c:?) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) read to 0xffffc90025a92344 of 4 bytes by task 4342 on cpu 4: kvm_vcpu_on_spin (arch/x86/kvm/../../../virt/kvm/kvm_main.c:4069) kvm handle_pause (arch/x86/kvm/vmx/vmx.c:5929) kvm_intel vmx_handle_exit (arch/x86/kvm/vmx/vmx.c:? arch/x86/kvm/vmx/vmx.c:6606) kvm_intel vcpu_run (arch/x86/kvm/x86.c:11107 arch/x86/kvm/x86.c:11211) kvm kvm_arch_vcpu_ioctl_run (arch/x86/kvm/x86.c:?) kvm kvm_vcpu_ioctl (arch/x86/kvm/../../../virt/kvm/kvm_main.c:?) kvm __se_sys_ioctl (fs/ioctl.c:52 fs/ioctl.c:904 fs/ioctl.c:890) __x64_sys_ioctl (fs/ioctl.c:890) x64_sys_call (arch/x86/entry/syscall_64.c:33) do_syscall_64 (arch/x86/entry/common.c:?) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) value changed: 0x00000012 -> 0x00000000

Gravité et risque d'exploitation

CVE-2024-40953 obtient un score CVSS de 7.9/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.20 %, ce qui la place devant 8.8 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.1.*, 6.10, <95c8dd79f3a14df96b3820b35b8399bd91b2be60, 5.15.169, 2.6.39, 5.4.285, 0, <4c141136a28421b78f34969b25a4fa32e06e2180, <49f683b41f28918df3e51ddc0d928cb2e934ccdb, <71fbc3af3dacb26c3aa2f30bb3ab05c44d082c84, <=5.10.*, <=6.6.*, <82bd728a06e55f5b5f93d10ce67f4fe7e689853a, 6.6.36, <=6.9.*, 6.9.7, 217ece6129f2d3b4fdd18d9e79be9e43d8d14a42, <=5.4.*, <=4.19.*, 4.19.323, <a937ef951bba72f48d2402451419d725d70dba20, 6.1.96, <11a772d5376aa6d3e2e69b5b5c585f79b60c0e17, <=*, <92c77807d938145c7c3350c944ef9f39d7f6017c, 5.10.228, <=5.15.*, <2.6.39) est présent sur votre parc.
• Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
• À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
• Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

• https://git.kernel.org/stable/c/11a772d5376aa6d3e2e69b5b5c585f79b60c0e17
• https://git.kernel.org/stable/c/4c141136a28421b78f34969b25a4fa32e06e2180
• https://git.kernel.org/stable/c/71fbc3af3dacb26c3aa2f30bb3ab05c44d082c84
• https://git.kernel.org/stable/c/82bd728a06e55f5b5f93d10ce67f4fe7e689853a
• https://git.kernel.org/stable/c/92c77807d938145c7c3350c944ef9f39d7f6017c
• https://git.kernel.org/stable/c/a937ef951bba72f48d2402451419d725d70dba20
• https://git.kernel.org/stable/c/95c8dd79f3a14df96b3820b35b8399bd91b2be60
• https://git.kernel.org/stable/c/49f683b41f28918df3e51ddc0d928cb2e934ccdb