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 636e625..ab37a18 100644 (file)
--- 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 a2c7502..2829ad4 100644 (file)
--- 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.