From: deraadt <deraadt@openbsd.org>
Date: Sat, 28 Dec 2013 03:22:52 +0000 (+0000)
Subject: change the stack protector guard into a long word (removing the old legacy
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=7da32b384eb34ea25ce176b88e8907165c6a27a0;p=openbsd

change the stack protector guard into a long word (removing the old legacy
compat pointed out by miod), and place it inside the ELF .openbsd.randomdata
segment.  Inside main(), only re-initialize the guard if the bootblocks
failed to initialize it for us.
---

diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index c26b9d4acef..703727b6985 100644
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: init_main.c,v 1.194 2013/12/28 03:12:56 deraadt Exp $	*/
+/*	$OpenBSD: init_main.c,v 1.195 2013/12/28 03:22:52 deraadt Exp $	*/
 /*	$NetBSD: init_main.c,v 1.84.4.1 1996/06/02 09:08:06 mrg Exp $	*/
 
 /*
@@ -132,10 +132,7 @@ int	ncpusfound = 1;			/* number of cpus we find */
 __volatile int start_init_exec;		/* semaphore for start_init() */
 
 #if !defined(NO_PROPOLICE)
-#ifdef __ELF__
-long	__guard_local __dso_hidden;
-#endif
-long	__guard[8];
+long	__guard_local __attribute__((section(".openbsd.randomdata")));
 #endif
 
 /* XXX return int so gcc -Werror won't complain */
@@ -415,16 +412,11 @@ main(void *framep)
 #endif
 
 #if !defined(NO_PROPOLICE)
-	{
-		volatile long newguard[8];
-
-		arc4random_buf((long *)newguard, sizeof(newguard));
+	if (__guard_local == 0) {
+		volatile long newguard;
 
-#ifdef __ELF__
-		__guard_local = newguard[0];
-#endif
-		for (i = nitems(__guard) - 1; i; i--)
-			__guard[i] = newguard[i];
+		newguard = arc4random();
+		__guard_local = newguard;
 	}
 #endif