CVE-2026-31442: Linux内核IDXD驱动内存访问漏洞

/* * Conceptual PoC for CVE-2026-31442 * This C code simulates the logic flaw in the idxd driver. * The vulnerability occurs when a deallocated pointer is not set to NULL, * leading to invalid access if a subsequent reallocation fails. */ #include <stdio.h> #include <stdlib.h> #include <string.h> typedef struct { int config_data; } device_config; device_config *scratch_area = NULL; // Simulates the vulnerable FLR (Function Level Reset) process void vulnerable_reset_sequence() { printf("[+] Starting First FLR...\n"); // First FLR: Allocation succeeds scratch_area = (device_config *)malloc(sizeof(device_config)); if (scratch_area) { scratch_area->config_data = 0x1234; printf("[+] First FLR: Scratch area allocated at %p\n", (void*)scratch_area); } // Simulate FLR completion and deallocation printf("[+] First FLR Complete. Freeing scratch area...\n"); free(scratch_area); // VULNERABILITY: The pointer is not set to NULL here. // scratch_area = NULL; <--- Missing fix printf("[-] Starting Second FLR...\n"); // Second FLR: Simulate allocation failure (e.g., memory pressure) // Force failure for demonstration device_config *new_area = (device_config *)malloc(sizeof(device_config)); if (new_area == NULL) { printf("[-] Second FLR: Allocation failed!\n"); // The code might check if scratch_area exists before trying to restore/validate // Since it was not NULLed, this condition passes, but the memory is invalid. if (scratch_area != NULL) { printf("[!] CRASH: Attempting to access invalid memory at %p\n", (void*)scratch_area); // This would cause a Use-After-Free or invalid access in kernel context int data = scratch_area->config_data; printf("Data: %d\n", data); // Unreachable in real crash scenario } } else { scratch_area = new_area; } } int main() { vulnerable_reset_sequence(); return 0; }