From: guenther <guenther@openbsd.org>
Date: Mon, 7 Feb 2022 19:30:48 +0000 (+0000)
Subject: Delete STACKGAPLEN: this exec-time allocation at the top of the
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=2f033923a701422d03b324678cbaa49598138bca;p=openbsd

Delete STACKGAPLEN: this exec-time allocation at the top of the
original thread's stack hasn't been used since 2015.

ok miod@ deraadt@
---

diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
index 636e625385f..ab37a18c8dd 100644
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_exec.c,v 1.228 2021/12/09 00:26:10 guenther Exp $	*/
+/*	$OpenBSD: kern_exec.c,v 1.229 2022/02/07 19:30:48 guenther Exp $	*/
 /*	$NetBSD: kern_exec.c,v 1.75 1996/02/09 18:59:28 christos Exp $	*/
 
 /*-
@@ -403,15 +403,15 @@ sys_execve(struct proc *p, void *v, register_t *retval)
 
 	dp = (char *)(((long)dp + _STACKALIGNBYTES) & ~_STACKALIGNBYTES);
 
-	sgap = STACKGAPLEN;
-
 	/*
 	 * If we have enabled random stackgap, the stack itself has already
 	 * been moved from a random location, but is still aligned to a page
 	 * boundary.  Provide the lower bits of random placement now.
 	 */
-	if (stackgap_random != 0) {
-		sgap += arc4random() & PAGE_MASK;
+	if (stackgap_random == 0) {
+		sgap = 0;
+	} else {
+		sgap = arc4random() & PAGE_MASK;
 		sgap = (sgap + _STACKALIGNBYTES) & ~_STACKALIGNBYTES;
 	}
 
diff --git a/sys/sys/exec.h b/sys/sys/exec.h
index a2c75023f81..2829ad490e0 100644
--- a/sys/sys/exec.h
+++ b/sys/sys/exec.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: exec.h,v 1.46 2021/12/09 00:26:10 guenther Exp $	*/
+/*	$OpenBSD: exec.h,v 1.47 2022/02/07 19:30:48 guenther Exp $	*/
 /*	$NetBSD: exec.h,v 1.59 1996/02/09 18:25:09 christos Exp $	*/
 
 /*-
@@ -57,12 +57,6 @@ struct ps_strings {
 	int	ps_nenvstr;	/* the number of environment strings */
 };
 
-/*
- * Below the PS_STRINGS and sigtramp, we may require a gap on the stack
- * (used to copyin/copyout various XXX emulation data structures).
- */
-#define	STACKGAPLEN	(2*1024)	/* plenty enough for now */
-
 /*
  * the following structures allow execve() to put together processes
  * in a more extensible and cleaner way.