Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932079AbWIAENJ (ORCPT ); Fri, 1 Sep 2006 00:13:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932083AbWIAENJ (ORCPT ); Fri, 1 Sep 2006 00:13:09 -0400 Received: from 1wt.eu ([62.212.114.60]:52241 "EHLO 1wt.eu") by vger.kernel.org with ESMTP id S932079AbWIAENH (ORCPT ); Fri, 1 Sep 2006 00:13:07 -0400 Date: Fri, 1 Sep 2006 05:48:34 +0200 From: Willy Tarreau To: Chris Snook Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH 2.4.33.2] enforce RLIMIT_NOFILE in poll() Message-ID: <20060901034834.GB28317@1wt.eu> References: <20060901.PbR.07536400@egw.corp.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060901.PbR.07536400@egw.corp.redhat.com> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2078 Lines: 46 Hi Chris, On Thu, Aug 31, 2006 at 09:06:55PM -0400, Chris Snook wrote: > From: Chris Snook > > POSIX states that poll() shall fail with EINVAL if nfds > OPEN_MAX. In this > context, POSIX is referring to sysconf(OPEN_MAX), which is the value of > current->rlim[RLIMIT_NOFILE].rlim_cur, not the compile-time constant which > happens to be named OPEN_MAX. The current code will permit polling up to 1024 > file descriptors even if RLIMIT_NOFILE is less than 1024, which POSIX forbids. > The current code also breaks polling greater than 1024 file descriptors if > the process has less than 1024 valid descriptors, even if RLIMIT_NOFILE > > 1024. While it is silly to poll duplicate or invalid file descriptors, POSIX > permits this, and it worked circa 2.4.18, and currently works up to 1024. > This patch directly checks the RLIMIT_NOFILE value, and permits exactly what > POSIX suggests, no more, no less. While I understand that it was a bug before, I fear that it could break existing apps. Are you aware of some apps which do not work as expected because of this bug ? If not, I'd prefer to wait for some feedback from 2.6 with this fix before applying it (or maybe you're already using it in RHEL with success ?). Thanks, Willy > Signed-off-by: Chris Snook > --- > > diff -urNp linux-2.4.33.2-orig/fs/select.c linux-2.4.33.2-patch/fs/select.c > --- linux-2.4.33.2-orig/fs/select.c 2006-08-22 16:13:54.000000000 -0400 > +++ linux-2.4.33.2-patch/fs/select.c 2006-08-31 13:43:39.000000000 -0400 > @@ -417,7 +417,7 @@ asmlinkage long sys_poll(struct pollfd * > int nchunks, nleft; > > /* Do a sanity check on nfds ... */ > - if (nfds > current->files->max_fdset && nfds > OPEN_MAX) > + if (nfds > current->rlim[RLIMIT_NOFILE].rlim_cur) > return -EINVAL; > > if (timeout) { - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/