From patchwork Fri Jan 6 01:17:55 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Williams X-Patchwork-Id: 9499815 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 6D387606DE for ; Fri, 6 Jan 2017 01:33:02 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6062728477 for ; Fri, 6 Jan 2017 01:33:02 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 54D0028497; Fri, 6 Jan 2017 01:33:02 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1C4C328477 for ; Fri, 6 Jan 2017 01:33:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751663AbdAFBct (ORCPT ); Thu, 5 Jan 2017 20:32:49 -0500 Received: from mga05.intel.com ([192.55.52.43]:64337 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751069AbdAFBcs (ORCPT ); Thu, 5 Jan 2017 20:32:48 -0500 Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga105.fm.intel.com with ESMTP; 05 Jan 2017 17:22:02 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,323,1477983600"; d="scan'208";a="50068702" Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.14]) by fmsmga005.fm.intel.com with ESMTP; 05 Jan 2017 17:22:01 -0800 Subject: [PATCH] block: fix blk_get_backing_dev_info() crash, use bdev->bd_queue From: Dan Williams To: axboe@fb.com Cc: Andi Kleen , Jan Kara , Rabin Vincent , linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux-block@vger.kernel.org, Jeff Moyer , Wei Fang , Christoph Hellwig Date: Thu, 05 Jan 2017 17:17:55 -0800 Message-ID: <148366547505.38941.646379357860772670.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.17.1-9-g687f MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The ->bd_queue member of struct block_device was added in commit 87192a2a49c4 ("vfs: cache request_queue in struct block_device") in v3.3. However, blk_get_backing_dev_info() has been using bdev_get_queue() and grabbing the request_queue through the gendisk since before the git era. At final __blkdev_put() time ->bd_disk is cleared while ->bd_queue is not. The queue remains valid until the final put of the parent disk. The following crash signature results from blk_get_backing_dev_info() trying to lookup the queue through ->bd_disk after the final put of the block device. Simply switch bdev_get_queue() to use ->bd_queue directly which is guaranteed to still be valid at invalidate_partition() time. BUG: unable to handle kernel NULL pointer dereference at 0000000000000568 IP: blk_get_backing_dev_info+0x10/0x20 [..] Call Trace: __inode_attach_wb+0x3a7/0x5d0 __filemap_fdatawrite_range+0xf8/0x100 filemap_write_and_wait+0x40/0x90 fsync_bdev+0x54/0x60 ? bdget_disk+0x30/0x40 invalidate_partition+0x24/0x50 del_gendisk+0xfa/0x230 Cc: Cc: Jan Kara Cc: Jens Axboe Cc: Jeff Moyer Cc: Christoph Hellwig Cc: Wei Fang Cc: Rabin Vincent Cc: Andi Kleen Fixes: 87192a2a49c4 ("vfs: cache request_queue in struct block_device") Signed-off-by: Dan Williams --- block/blk-core.c | 4 ++-- include/linux/blkdev.h | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/block/blk-core.c b/block/blk-core.c index 61ba08c58b64..04737548e1e1 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -109,8 +109,8 @@ void blk_queue_congestion_threshold(struct request_queue *q) * @bdev: device * * Locates the passed device's request queue and returns the address of its - * backing_dev_info. This function can only be called if @bdev is opened - * and the return value is never NULL. + * backing_dev_info. This function can only be called while there is an + * active reference against the parent gendisk. */ struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev) { diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 83695641bd5e..27779709f821 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -962,7 +962,7 @@ bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie); static inline struct request_queue *bdev_get_queue(struct block_device *bdev) { - return bdev->bd_disk->queue; /* this is never NULL */ + return bdev->bd_queue; /* this is never NULL */ } /*