From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754262Ab2AWXpK (ORCPT ); Mon, 23 Jan 2012 18:45:10 -0500 Received: from cantor2.suse.de ([195.135.220.15]:41925 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753654Ab2AWXpI (ORCPT ); Mon, 23 Jan 2012 18:45:08 -0500 X-Mailbox-Line: From gregkh@clark.kroah.org Mon Jan 23 15:42:02 2012 Message-Id: <20120123234202.693344341@clark.kroah.org> User-Agent: quilt/0.50-11.1 Date: Mon, 23 Jan 2012 15:40:58 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Ludwig Nussel , harvey.harrison@gmail.com, "H. Peter Anvin" , Ingo Molnar Subject: [12/27] x86: Fix mmap random address range In-Reply-To: <20120123234224.GA19510@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ From: Ludwig Nussel commit 9af0c7a6fa860698d080481f24a342ba74b68982 upstream. On x86_32 casting the unsigned int result of get_random_int() to long may result in a negative value. On x86_32 the range of mmap_rnd() therefore was -255 to 255. The 32bit mode on x86_64 used 0 to 255 as intended. The bug was introduced by 675a081 ("x86: unify mmap_{32|64}.c") in January 2008. Signed-off-by: Ludwig Nussel Cc: Linus Torvalds Cc: harvey.harrison@gmail.com Cc: "H. Peter Anvin" Cc: Harvey Harrison Signed-off-by: Andrew Morton Link: http://lkml.kernel.org/r/201111152246.pAFMklOB028527@wpaz5.hot.corp.google.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/mm/mmap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -87,9 +87,9 @@ static unsigned long mmap_rnd(void) */ if (current->flags & PF_RANDOMIZE) { if (mmap_is_ia32()) - rnd = (long)get_random_int() % (1<<8); + rnd = get_random_int() % (1<<8); else - rnd = (long)(get_random_int() % (1<<28)); + rnd = get_random_int() % (1<<28); } return rnd << PAGE_SHIFT; }