CVE-2026-31471 Linux内核xfrm释放后重用漏洞

/* * Conceptual PoC for CVE-2026-31471 * This PoC demonstrates the logic flaw where a failed allocation * leads to a dangling pointer in x->mode_data. * Triggering this requires local access and ability to manipulate * xfrm states and memory pressure. */ #include <stdio.h> #include <stdlib.h> #include <string.h> // Simulating the kernel structure behavior struct xfrm_state { void *mode_data; }; struct iptfs_state { int data; }; // Simulating the vulnerable function logic int vulnerable_iptfs_clone_state(struct xfrm_state *x) { struct iptfs_state *new_iptfs = malloc(sizeof(struct iptfs_state)); x->mode_data = new_iptfs; // 1. Store pointer before full setup // Simulate allocation failure for reorder window void *reorder_window = malloc(1024 * 1024 * 100); // Large alloc to fail easily if (!reorder_window) { free(new_iptfs); // 2. Free the state return -1; // 3. Return error, x->mode_data is now dangling } return 0; } void simulate_destroy_state(struct xfrm_state *x) { printf("Destroying state via mode_data: %p\n", x->mode_data); if (x->mode_data) { free(x->mode_data); // 4. Double Free / UAF occurs here printf("Double free triggered!\n"); } } int main() { struct xfrm_state x = {0}; printf("Triggering vulnerable clone path...\n"); int ret = vulnerable_iptfs_clone_state(&x); if (ret != 0) { printf("Clone failed (expected), unwinding...\n"); simulate_destroy_state(&x); // Trigger the vulnerability } return 0; }