CVE-2025-54771 GNU GRUB 释放后使用漏洞导致拒绝服务

/* * CVE-2025-54771 PoC - GNU GRUB Use-After-Free in file closing * This PoC demonstrates triggering the use-after-free condition * in GRUB's file handling module. * * Note: This requires local access to GRUB command line or * maliciously crafted boot configuration. */ #include <stdio.h> #include <stdlib.h> #include <string.h> /* Simulated GRUB file structure */ typedef struct grub_file { void *data; void *fs; char *name; int size; } grub_file_t; /* Vulnerable file close function - simulates the bug */ void grub_file_close_buggy(grub_file_t *file) { if (file == NULL) return; /* Free the filesystem structure - BUG: pointer not cleared */ if (file->fs != NULL) { free(file->fs); /* Missing: file->fs = NULL; */ } /* Free other resources */ if (file->data != NULL) free(file->data); if (file->name != NULL) free(file->name); /* Free file structure but fs pointer still references freed memory */ free(file); } /* Function that uses the dangling pointer */ void access_filesystem(grub_file_t *file) { /* This simulates accessing the freed fs pointer */ if (file->fs != NULL) { /* Use-after-free: accessing freed memory */ printf("Accessing filesystem at %p\n", file->fs); } } int main() { printf("CVE-2025-54771 PoC - GRUB Use-After-Free\n"); printf("======================================\n\n"); /* Simulate creating a file */ grub_file_t *file = (grub_file_t *)malloc(sizeof(grub_file_t)); file->fs = malloc(256); file->data = malloc(512); file->name = strdup("test.cfg"); file->size = 512; printf("[+] Created file object at %p\n", file); printf("[+] Filesystem pointer: %p\n", file->fs); /* Close file - triggers the bug */ printf("[*] Closing file...\n"); grub_file_close_buggy(file); /* Try to access the closed file - use-after-free */ printf("[!] Attempting to access closed file...\n"); access_filesystem(file); printf("\n[!] Use-after-free triggered - dangling pointer accessed\n"); printf("[!] This can cause crash or undefined behavior\n"); return 0; }