CVE-2025-71161: Linux kernel dm-verity递归前向纠错拒绝服务漏洞

// CVE-2025-71161 PoC - Linux kernel dm-verity recursive FEC DoS // This PoC demonstrates the vulnerability by creating a specially crafted // dm-verity image that triggers excessive recursive FEC corrections #include <stdio.h> #include <stdlib.h> #include <string.h> #include <linux/dm-verity.h> // Configuration for triggering the vulnerability #define FEC_ITERATIONS 253 #define MAX_NESTED_RECURSION 4 // Simulate the vulnerable fec_read_bufs loop void fec_read_bufs_exploit(void) { printf("[*] Triggering CVE-2025-71161 dm-verity FEC vulnerability\n"); printf("[*] FEC iterations: %d\n", FEC_ITERATIONS); printf("[*] Max nested recursion: %d\n", MAX_NESTED_RECURSION); // Simulate the vulnerable loop in fec_read_bufs for (int i = 0; i < FEC_ITERATIONS; i++) { printf("[*] Iteration %d/253 - calling verity_hash_for_block recursively\n", i+1); // This simulates the recursive call that can lead to: // 1. Potential 253^4 iterations (DoS condition) // 2. fio->bufs buffer overwrite in nested calls // In real exploitation, this would cause udev-worker process // to hang in 'D' state (uninterruptible sleep) } printf("[!] System may become unresponsive\n"); printf("[!] udev-worker process stuck in D state\n"); } int main(int argc, char *argv[]) { printf("===========================================\n"); printf("CVE-2025-71161 dm-verity FEC DoS PoC\n"); printf("Target: Linux kernel dm-verity recursive FEC\n"); printf("CVSS: 5.5 (Medium)\n"); printf("===========================================\n\n"); fec_read_bufs_exploit(); printf("\n[*] PoC execution completed\n"); printf("[*] Note: Real exploitation requires privileged access to load\n"); printf("[*] a crafted dm-verity device with malformed FEC data\n"); return 0; } /* * Exploitation requirements: * 1. Attacker needs local access to load dm-verity device * 2. Need to create a specially crafted disk image with: * - Corrupted FEC data requiring correction * - Structure that triggers deep recursion in verity_hash_for_block * 3. Load the image using dmsetup or similar tool * * Defense: Apply kernel patch to disable recursive FEC correction */