From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934216AbYB2V7R (ORCPT ); Fri, 29 Feb 2008 16:59:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932479AbYB2V7E (ORCPT ); Fri, 29 Feb 2008 16:59:04 -0500 Received: from smtp1.linux-foundation.org ([207.189.120.13]:55747 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932400AbYB2V7B (ORCPT ); Fri, 29 Feb 2008 16:59:01 -0500 Date: Fri, 29 Feb 2008 13:57:48 -0800 (PST) From: Linus Torvalds To: Michael Kerrisk cc: Peter Zijlstra , aaw , Andrew Morton , carlos@codesourcery.com, Alan Cox , linux-kernel , drepper@redhat.com, mtk.manpages@gmail.com, Geoff Clare Subject: Re: [RFC/PATCH] RLIMIT_ARG_MAX In-Reply-To: Message-ID: References: <1204119455.6242.403.camel@lappy> <1204305244.6243.111.camel@lappy> <1204307756.6243.121.camel@lappy> <47C84C6C.2000201@gmail.com> User-Agent: Alpine 1.00 (LFD 882 2007-12-20) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 29 Feb 2008, Linus Torvalds wrote: > > I do agree that we should at least make the "MAX(stacksize/4, 128k)" > change for backwards compatibility. How about something like this? The alternative is to just remove that size check entirely, and depend on get_user_pages() doing the stack limit check (among all the *other* checks it does when it does the acct_stack_growth() thing). I'd almost prefer that simpler approach, but I don't have any really strong preferences. Anybody? Linus --- fs/exec.c | 10 +++++++++- 1 files changed, 9 insertions(+), 1 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index a44b142..e91f9cb 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -173,8 +173,15 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, return NULL; if (write) { - struct rlimit *rlim = current->signal->rlim; unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start; + struct rlimit *rlim; + + /* + * We've historically supported up to 32 pages of argument + * strings even with small stacks + */ + if (size <= 32*PAGE_SIZE) + return page; /* * Limit to 1/4-th the stack size for the argv+env strings. @@ -183,6 +190,7 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, * - the program will have a reasonable amount of stack left * to work from. */ + rlim = current->signal->rlim; if (size > rlim[RLIMIT_STACK].rlim_cur / 4) { put_page(page); return NULL;