[src/trunk]: src/lib/libc/stdlib Note the problems with SSP.

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

details:   https://anonhg.NetBSD.org/src/rev/6af34b7df57b
branches:  trunk
changeset: 754530:6af34b7df57b
user:      jruoho <jruoho%NetBSD.org@localhost>
date:      Mon May 03 06:11:38 2010 +0000

description:
Note the problems with SSP.

diffstat:

 lib/libc/stdlib/alloca.3 |  20 ++++++++++++++++----
 1 files changed, 16 insertions(+), 4 deletions(-)

diffs (52 lines):

diff -r 2d0c203e720d -r 6af34b7df57b lib/libc/stdlib/alloca.3
--- a/lib/libc/stdlib/alloca.3  Mon May 03 05:53:56 2010 +0000
+++ b/lib/libc/stdlib/alloca.3  Mon May 03 06:11:38 2010 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: alloca.3,v 1.12 2003/08/07 16:43:37 agc Exp $
+.\"    $NetBSD: alloca.3,v 1.13 2010/05/03 06:11:38 jruoho Exp $
 .\"
 .\" Copyright (c) 1980, 1991, 1993
 .\"    The Regents of the University of California.  All rights reserved.
@@ -29,7 +29,7 @@
 .\"
 .\"     from: @(#)alloca.3     8.1 (Berkeley) 6/4/93
 .\"
-.Dd August 11, 2002
+.Dd May 3, 2010
 .Dt ALLOCA 3
 .Os
 .Sh NAME
@@ -63,12 +63,15 @@
 .Xr getpagesize 3 ,
 .Xr malloc 3 ,
 .Xr realloc 3
-.Sh BUGS
+.Sh CAVEATS
+Few limitations can be mentioned:
+.Bl -bullet
+.It
 The
 .Fn alloca
 function
 is machine dependent; its use is discouraged.
-.Pp
+.It
 The
 .Fn alloca
 function is slightly unsafe because it cannot ensure that the pointer
@@ -80,6 +83,15 @@
 Avoid
 .Fn alloca
 with large unbounded allocations.
+.It
+Since
+.Fn alloca
+modifies the stack at runtime,
+it causes problems to certain security features.
+See
+.Xr security 8
+for a discussion.
+.El
 .\" .Sh HISTORY
 .\" The
 .\" .Fn alloca