xref: /freebsd/sys/kern/stack_protector.c (revision 042df2e2dadea9f43b62b79ed97534c0eecf1dad)
1042df2e2SRuslan Ermilov #include <sys/cdefs.h>
2042df2e2SRuslan Ermilov __FBSDID("$FreeBSD$");
3042df2e2SRuslan Ermilov 
4042df2e2SRuslan Ermilov #include <sys/types.h>
5042df2e2SRuslan Ermilov #include <sys/param.h>
6042df2e2SRuslan Ermilov #include <sys/kernel.h>
7042df2e2SRuslan Ermilov #include <sys/systm.h>
8042df2e2SRuslan Ermilov #include <sys/libkern.h>
9042df2e2SRuslan Ermilov 
10042df2e2SRuslan Ermilov #if defined(__SSP__) || defined(__SSP_ALL__)
11042df2e2SRuslan Ermilov long __stack_chk_guard[8] = {};
12042df2e2SRuslan Ermilov void __stack_chk_fail(void);
13042df2e2SRuslan Ermilov 
14042df2e2SRuslan Ermilov void
15042df2e2SRuslan Ermilov __stack_chk_fail(void)
16042df2e2SRuslan Ermilov {
17042df2e2SRuslan Ermilov 
18042df2e2SRuslan Ermilov 	panic("stack overflow detected; backtrace may be corrupted");
19042df2e2SRuslan Ermilov }
20042df2e2SRuslan Ermilov 
21042df2e2SRuslan Ermilov #define __arraycount(__x)	(sizeof(__x) / sizeof(__x[0]))
22042df2e2SRuslan Ermilov static void
23042df2e2SRuslan Ermilov __stack_chk_init(void *dummy __unused)
24042df2e2SRuslan Ermilov {
25042df2e2SRuslan Ermilov 	size_t i;
26042df2e2SRuslan Ermilov 	long guard[__arraycount(__stack_chk_guard)];
27042df2e2SRuslan Ermilov 
28042df2e2SRuslan Ermilov 	arc4rand(guard, sizeof(guard), 0);
29042df2e2SRuslan Ermilov 	for (i = 0; i < __arraycount(guard); i++)
30042df2e2SRuslan Ermilov 		__stack_chk_guard[i] = guard[i];
31042df2e2SRuslan Ermilov }
32042df2e2SRuslan Ermilov /* SI_SUB_EVENTHANDLER is right after SI_SUB_LOCK used by arc4rand() init. */
33042df2e2SRuslan Ermilov SYSINIT(stack_chk, SI_SUB_EVENTHANDLER, SI_ORDER_ANY, __stack_chk_init, NULL);
34042df2e2SRuslan Ermilov 
35042df2e2SRuslan Ermilov #endif
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