From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 994F2C433F5 for ; Sat, 1 Jan 2022 18:41:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231189AbiAASks (ORCPT ); Sat, 1 Jan 2022 13:40:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37162 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229874AbiAASkr (ORCPT ); Sat, 1 Jan 2022 13:40:47 -0500 Received: from zeniv-ca.linux.org.uk (zeniv-ca.linux.org.uk [IPv6:2607:5300:60:148a::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7EA4AC061574 for ; Sat, 1 Jan 2022 10:40:47 -0800 (PST) Received: from viro by zeniv-ca.linux.org.uk with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1n3jJ0-00GTbv-S5; Sat, 01 Jan 2022 18:40:39 +0000 Date: Sat, 1 Jan 2022 18:40:38 +0000 From: Al Viro To: Greg Kroah-Hartman Cc: kernel test robot , devel@driverdev.osuosl.org, kbuild-all@lists.01.org, linux-kernel@vger.kernel.org Subject: Re: [driver-core:debugfs_cleanup 4/5] fs/d_path.c:59 prepend() warn: unsigned 'p->len' is never less than zero. Message-ID: References: <202201010156.bJvO7Gaw-lkp@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: Al Viro Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jan 01, 2022 at 02:08:54PM +0100, Greg Kroah-Hartman wrote: > On Fri, Dec 31, 2021 at 07:35:07PM +0000, Al Viro wrote: > > On Sat, Jan 01, 2022 at 01:08:41AM +0800, kernel test robot wrote: > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git debugfs_cleanup > > > head: a04bbe0a2c7e98669e11a47f94e53dd8228bbeba > > > commit: e95d5bed5d58c2f5352969369827e7135fa2261e [4/5] fs: make d_path-like functions all have unsigned size > > > config: i386-randconfig-m031-20211228 (https://download.01.org/0day-ci/archive/20220101/202201010156.bJvO7Gaw-lkp@intel.com/config) > > > compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 > > > > > > If you fix the issue, kindly add following tag as appropriate > > > Reported-by: kernel test robot > > > > > > smatch warnings: > > > fs/d_path.c:59 prepend() warn: unsigned 'p->len' is never less than zero. > > > > What do you mean, "unsigned p->len"? > > > > ->len really *can* be negative - that's how running out of buffer is indicated. > > > > Greg, I stand by the comment I made back in July - this kind of "hardening" is > > useless; there's no legitimate reason to pass a huge buffer length, especially > > since there's a limit on the length of pathname any syscall would accept. > > See https://www.spinics.net/lists/linux-fsdevel/msg200370.html for the > > variant I would prefer. > > Sorry, yes, I agree with you, but never deleted this commit from this > "scratch" branch of mine. I'll go rebase the branch and purge it from > the system so that 0-day doesn't hit it anymore, sorry for the noise. OK... I'll probably throw something along the lines of "negative => EINVAL, positive greater than 32Kb - adjust the buffer and length to the last 32Kb of what had been passed" into the misc queue.