From owner-svn-src-stable@FreeBSD.ORG Sun Nov 21 09:50:12 2010 Return-Path: Delivered-To: svn-src-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 665E2106564A; Sun, 21 Nov 2010 09:50:12 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c]) by mx1.freebsd.org (Postfix) with ESMTP id 3A44C8FC08; Sun, 21 Nov 2010 09:50:12 +0000 (UTC) Received: from svn.freebsd.org (localhost [127.0.0.1]) by svn.freebsd.org (8.14.3/8.14.3) with ESMTP id oAL9oCF1042979; Sun, 21 Nov 2010 09:50:12 GMT (envelope-from kib@svn.freebsd.org) Received: (from kib@localhost) by svn.freebsd.org (8.14.3/8.14.3/Submit) id oAL9oCp1042977; Sun, 21 Nov 2010 09:50:12 GMT (envelope-from kib@svn.freebsd.org) Message-Id: <201011210950.oAL9oCp1042977@svn.freebsd.org> From: Konstantin Belousov Date: Sun, 21 Nov 2010 09:50:12 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-8@freebsd.org X-SVN-Group: stable-8 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: Subject: svn commit: r215608 - stable/8/sys/vm X-BeenThere: svn-src-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: SVN commit messages for all the -stable branches of the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 21 Nov 2010 09:50:12 -0000 Author: kib Date: Sun Nov 21 09:50:11 2010 New Revision: 215608 URL: http://svn.freebsd.org/changeset/base/215608 Log: MFC r215307: Implement a (soft) stack guard page for auto-growing stack mappings. Modified: stable/8/sys/vm/vm_map.c Directory Properties: stable/8/sys/ (props changed) stable/8/sys/amd64/include/xen/ (props changed) stable/8/sys/cddl/contrib/opensolaris/ (props changed) stable/8/sys/contrib/dev/acpica/ (props changed) stable/8/sys/contrib/pf/ (props changed) stable/8/sys/dev/xen/xenpci/ (props changed) Modified: stable/8/sys/vm/vm_map.c ============================================================================== --- stable/8/sys/vm/vm_map.c Sun Nov 21 04:02:37 2010 (r215607) +++ stable/8/sys/vm/vm_map.c Sun Nov 21 09:50:11 2010 (r215608) @@ -67,6 +67,7 @@ __FBSDID("$FreeBSD$"); #include #include +#include #include #include #include @@ -76,6 +77,7 @@ __FBSDID("$FreeBSD$"); #include #include #include +#include #include #include @@ -3221,6 +3223,12 @@ vm_map_stack(vm_map_t map, vm_offset_t a return (rv); } +static int stack_guard_page = 0; +TUNABLE_INT("security.bsd.stack_guard_page", &stack_guard_page); +SYSCTL_INT(_security_bsd, OID_AUTO, stack_guard_page, CTLFLAG_RW, + &stack_guard_page, 0, + "Insert stack guard page ahead of the growable segments."); + /* Attempts to grow a vm stack entry. Returns KERN_SUCCESS if the * desired address is already mapped, or if we successfully grow * the stack. Also returns KERN_SUCCESS if addr is outside the @@ -3317,7 +3325,7 @@ Retry: * This also effectively destroys any guard page the user might have * intended by limiting the stack size. */ - if (grow_amount > max_grow) { + if (grow_amount + (stack_guard_page ? PAGE_SIZE : 0) > max_grow) { if (vm_map_lock_upgrade(map)) goto Retry; @@ -3370,6 +3378,8 @@ Retry: if (addr < end) { stack_entry->avail_ssize = max_grow; addr = end; + if (stack_guard_page) + addr += PAGE_SIZE; } rv = vm_map_insert(map, NULL, 0, addr, stack_entry->start, @@ -3402,6 +3412,8 @@ Retry: if (addr > end) { stack_entry->avail_ssize = end - stack_entry->end; addr = end; + if (stack_guard_page) + addr -= PAGE_SIZE; } grow_amount = addr - stack_entry->end;