From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965789Ab1KJDqY (ORCPT ); Wed, 9 Nov 2011 22:46:24 -0500 Received: from cantor2.suse.de ([195.135.220.15]:44874 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965775Ab1KJDqS (ORCPT ); Wed, 9 Nov 2011 22:46:18 -0500 X-Mailbox-Line: From gregkh@clark.kroah.org Wed Nov 9 13:32:03 2011 Message-Id: <20111109213203.558056268@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Wed, 09 Nov 2011 13:34:17 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Christoph Hellwig , Andy Grover , Nicholas Bellinger Subject: [210/264] tcm_loop: Add explict read buffer memset for SCF_SCSI_CONTROL_SG_IO_CDB In-Reply-To: <20111109213508.GA3476@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nicholas Bellinger commit 8cd79f24350826b81e16990d9e12bc878e67d385 upstream. This patch addresses an issue with buggy userspace code sending I/O via scsi-generic that does not explictly clear their associated read buffers. It adds an explict memset of the first SGL entry within tcm_loop_new_cmd_map() for SCF_SCSI_CONTROL_SG_IO_CDB payloads that are currently guaranteed to be a single SGL by target-core code. This issue is a side effect of the v3.1-rc1 merge to remove the extra memcpy between certain control CDB types using a contigious + cleared buffer in target-core, and performing a memcpy into the SGL list within tcm_loop. It was originally mainfesting itself by udev + scsi_id + scsi-generic not properly setting up the expected /dev/disk/by-id/ symlinks because the INQUIRY payload was containing extra bogus data preventing the proper NAA IEEE WWN from being parsed by userspace. Cc: Christoph Hellwig Cc: Andy Grover Signed-off-by: Nicholas Bellinger Signed-off-by: Greg Kroah-Hartman --- drivers/target/loopback/tcm_loop.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) --- a/drivers/target/loopback/tcm_loop.c +++ b/drivers/target/loopback/tcm_loop.c @@ -174,6 +174,24 @@ static int tcm_loop_new_cmd_map(struct s sgl_bidi = sdb->table.sgl; sgl_bidi_count = sdb->table.nents; } + /* + * Because some userspace code via scsi-generic do not memset their + * associated read buffers, go ahead and do that here for type + * SCF_SCSI_CONTROL_SG_IO_CDB. Also note that this is currently + * guaranteed to be a single SGL for SCF_SCSI_CONTROL_SG_IO_CDB + * by target core in transport_generic_allocate_tasks() -> + * transport_generic_cmd_sequencer(). + */ + if (se_cmd->se_cmd_flags & SCF_SCSI_CONTROL_SG_IO_CDB && + se_cmd->data_direction == DMA_FROM_DEVICE) { + struct scatterlist *sg = scsi_sglist(sc); + unsigned char *buf = kmap(sg_page(sg)) + sg->offset; + + if (buf != NULL) { + memset(buf, 0, sg->length); + kunmap(sg_page(sg)); + } + } /* Tell the core about our preallocated memory */ ret = transport_generic_map_mem_to_cmd(se_cmd, scsi_sglist(sc),