1180012Sru#include <sys/cdefs.h>
2180012Sru__FBSDID("$FreeBSD$");
3180012Sru
4180012Sru#include <sys/types.h>
5180012Sru#include <sys/param.h>
6180012Sru#include <sys/kernel.h>
7180012Sru#include <sys/systm.h>
8180012Sru#include <sys/libkern.h>
9180012Sru
10180012Srulong __stack_chk_guard[8] = {};
11180012Sruvoid __stack_chk_fail(void);
12180012Sru
13180012Sruvoid
14180012Sru__stack_chk_fail(void)
15180012Sru{
16180012Sru
17180012Sru	panic("stack overflow detected; backtrace may be corrupted");
18180012Sru}
19180012Sru
20180012Sru#define __arraycount(__x)	(sizeof(__x) / sizeof(__x[0]))
21180012Srustatic void
22180012Sru__stack_chk_init(void *dummy __unused)
23180012Sru{
24180012Sru	size_t i;
25180012Sru	long guard[__arraycount(__stack_chk_guard)];
26180012Sru
27180012Sru	arc4rand(guard, sizeof(guard), 0);
28180012Sru	for (i = 0; i < __arraycount(guard); i++)
29180012Sru		__stack_chk_guard[i] = guard[i];
30180012Sru}
31198295SruSYSINIT(stack_chk, SI_SUB_RANDOM, SI_ORDER_ANY, __stack_chk_init, NULL);
32