[src/trunk]: src/sys/kern Fix stack allocation; limit delta to a quarter of t...

[christos <christos%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/0f2bc225f576
branches:  trunk
changeset: 345124:0f2bc225f576
user:      christos <christos%NetBSD.org@localhost>
date:      Sun May 08 20:01:56 2016 +0000

description:
Fix stack allocation; limit delta to a quarter of the stack size. This should
get rid of the random aborts.

diffstat:

 sys/kern/kern_pax.c |  7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diffs (28 lines):

diff -r d9f8fe3fd938 -r 0f2bc225f576 sys/kern/kern_pax.c
--- a/sys/kern/kern_pax.c       Sun May 08 20:00:21 2016 +0000
+++ b/sys/kern/kern_pax.c       Sun May 08 20:01:56 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_pax.c,v 1.42 2016/05/08 01:28:09 christos Exp $   */
+/*     $NetBSD: kern_pax.c,v 1.43 2016/05/08 20:01:56 christos Exp $   */
 
 /*
  * Copyright (c) 2015 The NetBSD Foundation, Inc.
@@ -57,7 +57,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_pax.c,v 1.42 2016/05/08 01:28:09 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_pax.c,v 1.43 2016/05/08 20:01:56 christos Exp $");
 
 #include "opt_pax.h"
 
@@ -564,7 +564,8 @@
                rand = pax_aslr_rand;
 #endif
        u_long d = PAX_ASLR_DELTA(rand, PAX_ASLR_DELTA_STACK_LSB, len);
-       u_long newminsaddr = (u_long)STACK_ALLOC(epp->ep_minsaddr, d);
+       d &= (*max_stack_size / 4) - 1;
+       u_long newminsaddr = (u_long)STACK_GROW(epp->ep_minsaddr, d);
        PAX_DPRINTF("old minsaddr=%#jx delta=%#lx new minsaddr=%#lx",
            (uintmax_t)epp->ep_minsaddr, d, newminsaddr);
        epp->ep_minsaddr = (vaddr_t)newminsaddr;