Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1039205AbdDUM2a (ORCPT ); Fri, 21 Apr 2017 08:28:30 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:33928 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1037137AbdDUM20 (ORCPT ); Fri, 21 Apr 2017 08:28:26 -0400 Subject: Re: Unchecked flags in statx(2) [Should be fixed before 4.11-final?] To: David Howells References: Cc: mtk.manpages@gmail.com, lkml , linux-fsdevel , hch@infradead.org, Eric Biggers , Linux API , Alexander Viro From: "Michael Kerrisk (man-pages)" Message-ID: Date: Fri, 21 Apr 2017 14:28:22 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1261 Lines: 37 [Adding a few people to CC, and correcting myself on one piece] On 04/21/2017 02:14 PM, Michael Kerrisk (man-pages) wrote: > Hello David, > > I was reading your statx(2) man page, and noticed this text: > > Do not simply set mask to UINT_MAX as one or more bits may, in the > future, be used to specify an extension to the buffer. > > (Here' 'mask' is the fourth argument to statx()) > > What is going on here? Why is there not a check in the code to > give EINVAL if any flag other than those in STATX_ALL (0x00000fffU) > is specified? (There is a check that gives EINVAL flags in > STATX__RESERVED (0x80000000U), but STATX_ALL != ~STATX__RESERVED. > > Similarly, there appears to be no check for invalid flags in the > 'flags' argument of statx(). Why is there also not such a check > there? > > The failure to do these sorts of checks has been the source of grief > in the past with other system calls. So, it looks like the checks are there for 'flags' (I missed that they were one level deeper in the call sequence), but my question re 'mask' still stands. Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/