From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: LIBATA SCSI command validation changed in 2.6.24 Date: Fri, 11 Jan 2008 18:21:42 -0500 Message-ID: <4787FA06.9090204@garzik.org> References: <4787DFE2.2000504@redhat.com> <4787E114.2030301@garzik.org> <4787E574.6020304@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:50712 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759573AbYAKXVp (ORCPT ); Fri, 11 Jan 2008 18:21:45 -0500 In-Reply-To: <4787E574.6020304@redhat.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Chuck Ebbert Cc: linux-kernel , IDE/ATA development list Chuck Ebbert wrote: > On 01/11/2008 04:35 PM, Jeff Garzik wrote: >> Chuck Ebbert wrote: >>> commit 607126c2a21cd6e9bb807fdd415c1a992f7b9009 changed command >>> validation >>> to allow short commands in 16-byte CDBs, but it also made checking more >>> strict. Before the change, a 10-byte SG_IO command could have its >>> length set >>> to 9 and still work. Now it fails. Not sure if this is a bug, but it has >>> caused at least one application to fail that used to work (qpxtool.) >>> >>> [https://bugzilla.redhat.com/show_bug.cgi?id=428281] >> Can you get us an example CDB? Its unclear if the hexdump in the bug >> report is a returned mode page or the CDB or what...? >> > > Not easily, but the maintainer of that program forced the length of > the MODE_SENSE(10) command to 10 and that command started working. > > By looking at the source I could tell that it was setting the command > length to (1 + the index of the last byte written to the CDB) and > only wrote up to offset 8 when building the command, so it must have > been sending the command with a length of 9. (It zeroed the whole CDB > first and only wrote what it needed to.) > > (And it used the C++ operator [] to build the command, that was fun > to trace...) Even if allocation length is present in the CDB, the CDB may be missing important information that is required to process the command. So it may have caught a bug in the program... depending on the CDB. Jeff