From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7DC53C282C3 for ; Thu, 24 Jan 2019 19:24:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 44F2D217D7 for ; Thu, 24 Jan 2019 19:24:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548357844; bh=YUvnAihcms6DTIkevkfZuTRr3rDgWlxdN5XuQVnXtSs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ZXh4R3TQpQsbxA52OYALP+RVibsRZLBiR8LB1knU6/SokbMqjXKVqUoGBRZeTVq7i DSVaaOq8nVnOsWN8GKfATkMzKXIw8UTyhHQDD0sTt2qspcoYmlzdZd8VpECffIwYog QFU+/VfZpCn/cO2grEaNcBFY56s1Bt8jhcxn1HkY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729990AbfAXTYC (ORCPT ); Thu, 24 Jan 2019 14:24:02 -0500 Received: from mail.kernel.org ([198.145.29.99]:48968 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729461AbfAXTX4 (ORCPT ); Thu, 24 Jan 2019 14:23:56 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 91806218EA; Thu, 24 Jan 2019 19:23:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548357835; bh=YUvnAihcms6DTIkevkfZuTRr3rDgWlxdN5XuQVnXtSs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=u6AZHpp3iYo61e1Z++PQzE3Jizux8b+MOzItBlrmalobEWXvbTUm5UwuAIksQetN/ P9oTL4RultovVq7aQglcGDor1Ek0obdl20GQP90QahQGHSG5wFwgnMrxHJtnnQ7bvx 8hYWMuM/QC2bOYtG7I0K4iQqgr0pyUUb3rvc/12E= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tetsuo Handa , syzbot , Jan Kara , Jens Axboe Subject: [PATCH 3.18 31/52] block/loop: Use global lock for ioctl() operation. Date: Thu, 24 Jan 2019 20:19:55 +0100 Message-Id: <20190124190147.778778015@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190124190140.879495253@linuxfoundation.org> References: <20190124190140.879495253@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tetsuo Handa commit 310ca162d779efee8a2dc3731439680f3e9c1e86 upstream. syzbot is reporting NULL pointer dereference [1] which is caused by race condition between ioctl(loop_fd, LOOP_CLR_FD, 0) versus ioctl(other_loop_fd, LOOP_SET_FD, loop_fd) due to traversing other loop devices at loop_validate_file() without holding corresponding lo->lo_ctl_mutex locks. Since ioctl() request on loop devices is not frequent operation, we don't need fine grained locking. Let's use global lock in order to allow safe traversal at loop_validate_file(). Note that syzbot is also reporting circular locking dependency between bdev->bd_mutex and lo->lo_ctl_mutex [2] which is caused by calling blkdev_reread_part() with lock held. This patch does not address it. [1] https://syzkaller.appspot.com/bug?id=f3cfe26e785d85f9ee259f385515291d21bd80a3 [2] https://syzkaller.appspot.com/bug?id=bf154052f0eea4bc7712499e4569505907d15889 Signed-off-by: Tetsuo Handa Reported-by: syzbot Reviewed-by: Jan Kara Signed-off-by: Jan Kara Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- drivers/block/loop.c | 47 ++++++++++++++++++++++++----------------------- drivers/block/loop.h | 1 - 2 files changed, 24 insertions(+), 24 deletions(-) --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -81,6 +81,7 @@ static DEFINE_IDR(loop_index_idr); static DEFINE_MUTEX(loop_index_mutex); +static DEFINE_MUTEX(loop_ctl_mutex); static int max_part; static int part_shift; @@ -1012,7 +1013,7 @@ static int loop_clr_fd(struct loop_devic */ if (lo->lo_refcnt > 1) { lo->lo_flags |= LO_FLAGS_AUTOCLEAR; - mutex_unlock(&lo->lo_ctl_mutex); + mutex_unlock(&loop_ctl_mutex); return 0; } @@ -1061,12 +1062,12 @@ static int loop_clr_fd(struct loop_devic lo->lo_flags = 0; if (!part_shift) lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN; - mutex_unlock(&lo->lo_ctl_mutex); + mutex_unlock(&loop_ctl_mutex); /* - * Need not hold lo_ctl_mutex to fput backing file. - * Calling fput holding lo_ctl_mutex triggers a circular + * Need not hold loop_ctl_mutex to fput backing file. + * Calling fput holding loop_ctl_mutex triggers a circular * lock dependency possibility warning as fput can take - * bd_mutex which is usually taken before lo_ctl_mutex. + * bd_mutex which is usually taken before loop_ctl_mutex. */ fput(filp); return 0; @@ -1300,7 +1301,7 @@ static int lo_ioctl(struct block_device struct loop_device *lo = bdev->bd_disk->private_data; int err; - mutex_lock_nested(&lo->lo_ctl_mutex, 1); + mutex_lock_nested(&loop_ctl_mutex, 1); switch (cmd) { case LOOP_SET_FD: err = loop_set_fd(lo, mode, bdev, arg); @@ -1309,7 +1310,7 @@ static int lo_ioctl(struct block_device err = loop_change_fd(lo, bdev, arg); break; case LOOP_CLR_FD: - /* loop_clr_fd would have unlocked lo_ctl_mutex on success */ + /* loop_clr_fd would have unlocked loop_ctl_mutex on success */ err = loop_clr_fd(lo); if (!err) goto out_unlocked; @@ -1340,7 +1341,7 @@ static int lo_ioctl(struct block_device default: err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL; } - mutex_unlock(&lo->lo_ctl_mutex); + mutex_unlock(&loop_ctl_mutex); out_unlocked: return err; @@ -1473,16 +1474,16 @@ static int lo_compat_ioctl(struct block_ switch(cmd) { case LOOP_SET_STATUS: - mutex_lock(&lo->lo_ctl_mutex); + mutex_lock(&loop_ctl_mutex); err = loop_set_status_compat( lo, (const struct compat_loop_info __user *) arg); - mutex_unlock(&lo->lo_ctl_mutex); + mutex_unlock(&loop_ctl_mutex); break; case LOOP_GET_STATUS: - mutex_lock(&lo->lo_ctl_mutex); + mutex_lock(&loop_ctl_mutex); err = loop_get_status_compat( lo, (struct compat_loop_info __user *) arg); - mutex_unlock(&lo->lo_ctl_mutex); + mutex_unlock(&loop_ctl_mutex); break; case LOOP_SET_CAPACITY: case LOOP_CLR_FD: @@ -1513,9 +1514,9 @@ static int lo_open(struct block_device * goto out; } - mutex_lock(&lo->lo_ctl_mutex); + mutex_lock(&loop_ctl_mutex); lo->lo_refcnt++; - mutex_unlock(&lo->lo_ctl_mutex); + mutex_unlock(&loop_ctl_mutex); out: mutex_unlock(&loop_index_mutex); return err; @@ -1525,7 +1526,7 @@ static void __lo_release(struct loop_dev { int err; - mutex_lock(&lo->lo_ctl_mutex); + mutex_lock(&loop_ctl_mutex); if (--lo->lo_refcnt) goto out; @@ -1547,7 +1548,7 @@ static void __lo_release(struct loop_dev } out: - mutex_unlock(&lo->lo_ctl_mutex); + mutex_unlock(&loop_ctl_mutex); } static void lo_release(struct gendisk *disk, fmode_t mode) @@ -1593,10 +1594,10 @@ static int unregister_transfer_cb(int id struct loop_device *lo = ptr; struct loop_func_table *xfer = data; - mutex_lock(&lo->lo_ctl_mutex); + mutex_lock(&loop_ctl_mutex); if (lo->lo_encryption == xfer) loop_release_xfer(lo); - mutex_unlock(&lo->lo_ctl_mutex); + mutex_unlock(&loop_ctl_mutex); return 0; } @@ -1677,7 +1678,7 @@ static int loop_add(struct loop_device * if (!part_shift) disk->flags |= GENHD_FL_NO_PART_SCAN; disk->flags |= GENHD_FL_EXT_DEVT; - mutex_init(&lo->lo_ctl_mutex); + mutex_init(&loop_ctl_mutex); lo->lo_number = i; lo->lo_thread = NULL; init_waitqueue_head(&lo->lo_event); @@ -1789,19 +1790,19 @@ static long loop_control_ioctl(struct fi ret = loop_lookup(&lo, parm); if (ret < 0) break; - mutex_lock(&lo->lo_ctl_mutex); + mutex_lock(&loop_ctl_mutex); if (lo->lo_state != Lo_unbound) { ret = -EBUSY; - mutex_unlock(&lo->lo_ctl_mutex); + mutex_unlock(&loop_ctl_mutex); break; } if (lo->lo_refcnt > 0) { ret = -EBUSY; - mutex_unlock(&lo->lo_ctl_mutex); + mutex_unlock(&loop_ctl_mutex); break; } lo->lo_disk->private_data = NULL; - mutex_unlock(&lo->lo_ctl_mutex); + mutex_unlock(&loop_ctl_mutex); idr_remove(&loop_index_idr, lo->lo_number); loop_remove(lo); break; --- a/drivers/block/loop.h +++ b/drivers/block/loop.h @@ -55,7 +55,6 @@ struct loop_device { struct bio_list lo_bio_list; unsigned int lo_bio_count; int lo_state; - struct mutex lo_ctl_mutex; struct task_struct *lo_thread; wait_queue_head_t lo_event; /* wait queue for incoming requests */