From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757729Ab0LHBYb (ORCPT ); Tue, 7 Dec 2010 20:24:31 -0500 Received: from kroah.org ([198.145.64.141]:33512 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932434Ab0LHBCo (ORCPT ); Tue, 7 Dec 2010 20:02:44 -0500 X-Mailbox-Line: From gregkh@clark.site Tue Dec 7 16:57:40 2010 Message-Id: <20101208005740.387428982@clark.site> User-Agent: quilt/0.48-11.2 Date: Tue, 07 Dec 2010 16:59:26 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Tejun Heo , Jeff Garzik Subject: [189/289] libata: fix NULL sdev dereference race in atapi_qc_complete() In-Reply-To: <20101208005821.GA2922@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.36-stable review patch. If anyone has any objections, please let us know. ------------------ From: Tejun Heo commit 2a5f07b5ec098edc69e05fdd2f35d3fbb1235723 upstream. SCSI commands may be issued between __scsi_add_device() and dev->sdev assignment, so it's unsafe for ata_qc_complete() to dereference dev->sdev->locked without checking whether it's NULL or not. Fix it. Signed-off-by: Tejun Heo Signed-off-by: Jeff Garzik Signed-off-by: Greg Kroah-Hartman --- drivers/ata/libata-scsi.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -2577,8 +2577,11 @@ static void atapi_qc_complete(struct ata * * If door lock fails, always clear sdev->locked to * avoid this infinite loop. + * + * This may happen before SCSI scan is complete. Make + * sure qc->dev->sdev isn't NULL before dereferencing. */ - if (qc->cdb[0] == ALLOW_MEDIUM_REMOVAL) + if (qc->cdb[0] == ALLOW_MEDIUM_REMOVAL && qc->dev->sdev) qc->dev->sdev->locked = 0; qc->scsicmd->result = SAM_STAT_CHECK_CONDITION;