From patchwork Thu Aug 17 20:12:45 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bart Van Assche X-Patchwork-Id: 9907027 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 23E26603B5 for ; Thu, 17 Aug 2017 20:15:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 17CD228BC5 for ; Thu, 17 Aug 2017 20:15:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0CBB128BD2; Thu, 17 Aug 2017 20:15:20 +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 A457C28BD0 for ; Thu, 17 Aug 2017 20:15:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753741AbdHQUOf (ORCPT ); Thu, 17 Aug 2017 16:14:35 -0400 Received: from esa4.hgst.iphmx.com ([216.71.154.42]:33267 "EHLO esa4.hgst.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753737AbdHQUOe (ORCPT ); Thu, 17 Aug 2017 16:14:34 -0400 X-IronPort-AV: E=Sophos;i="5.41,389,1498492800"; d="scan'208";a="43185992" Received: from sjappemgw12.hgst.com (HELO sjappemgw11.hgst.com) ([199.255.44.66]) by ob1.hgst.iphmx.com with ESMTP; 18 Aug 2017 04:13:47 +0800 Received: from thinkpad-bart.sdcorp.global.sandisk.com (HELO thinkpad-bart.int.fusionio.com) ([10.11.172.152]) by sjappemgw11.hgst.com with ESMTP; 17 Aug 2017 13:13:39 -0700 From: Bart Van Assche To: Jens Axboe Cc: linux-block@vger.kernel.org, Christoph Hellwig , Damien Le Moal , Akhil Bhansali , Bart Van Assche , Hannes Reinecke , Johannes Thumshirn , stable@vger.kernel.org Subject: [PATCH 02/55] skd: Avoid that module unloading triggers a use-after-free Date: Thu, 17 Aug 2017 13:12:45 -0700 Message-Id: <20170817201338.16537-3-bart.vanassche@wdc.com> X-Mailer: git-send-email 2.14.0 In-Reply-To: <20170817201338.16537-1-bart.vanassche@wdc.com> References: <20170817201338.16537-1-bart.vanassche@wdc.com> 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 Since put_disk() triggers a disk_release() call and since that last function calls blk_put_queue() if disk->queue != NULL, clear the disk->queue pointer before calling put_disk(). This avoids that unloading the skd kernel module triggers the following use-after-free: WARNING: CPU: 8 PID: 297 at lib/refcount.c:128 refcount_sub_and_test+0x70/0x80 refcount_t: underflow; use-after-free. CPU: 8 PID: 297 Comm: kworker/8:1 Not tainted 4.11.10-300.fc26.x86_64 #1 Workqueue: events work_for_cpu_fn Call Trace: dump_stack+0x63/0x84 __warn+0xcb/0xf0 warn_slowpath_fmt+0x5a/0x80 refcount_sub_and_test+0x70/0x80 refcount_dec_and_test+0x11/0x20 kobject_put+0x1f/0x50 blk_put_queue+0x15/0x20 disk_release+0xae/0xf0 device_release+0x32/0x90 kobject_release+0x67/0x170 kobject_put+0x2b/0x50 put_disk+0x17/0x20 skd_destruct+0x5c/0x890 [skd] skd_pci_probe+0x124d/0x13a0 [skd] local_pci_probe+0x42/0xa0 work_for_cpu_fn+0x14/0x20 process_one_work+0x19e/0x470 worker_thread+0x1dc/0x4a0 kthread+0x125/0x140 ret_from_fork+0x25/0x30 Signed-off-by: Bart Van Assche Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Johannes Thumshirn Cc: --- drivers/block/skd_main.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/drivers/block/skd_main.c b/drivers/block/skd_main.c index d0368682bd43..edab9c04e8ad 100644 --- a/drivers/block/skd_main.c +++ b/drivers/block/skd_main.c @@ -4539,15 +4539,16 @@ static void skd_free_disk(struct skd_device *skdev) { struct gendisk *disk = skdev->disk; - if (disk != NULL) { - struct request_queue *q = disk->queue; - - if (disk->flags & GENHD_FL_UP) - del_gendisk(disk); - if (q) - blk_cleanup_queue(q); - put_disk(disk); + if (disk && (disk->flags & GENHD_FL_UP)) + del_gendisk(disk); + + if (skdev->queue) { + blk_cleanup_queue(skdev->queue); + skdev->queue = NULL; + disk->queue = NULL; } + + put_disk(disk); skdev->disk = NULL; }