From patchwork Tue Nov 15 14:10:52 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 13043744 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7A987C4321E for ; Tue, 15 Nov 2022 13:49:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230118AbiKONto (ORCPT ); Tue, 15 Nov 2022 08:49:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49704 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238116AbiKONth (ORCPT ); Tue, 15 Nov 2022 08:49:37 -0500 Received: from dggsgout11.his.huawei.com (unknown [45.249.212.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E1760264A7; Tue, 15 Nov 2022 05:49:35 -0800 (PST) Received: from mail02.huawei.com (unknown [172.30.67.153]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4NBSGK2h05z4f3kJs; Tue, 15 Nov 2022 21:49:29 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.127.227]) by APP4 (Coremail) with SMTP id gCh0CgBni9jnmHNjrPFIAg--.61645S12; Tue, 15 Nov 2022 21:49:32 +0800 (CST) From: Yu Kuai To: hch@lst.de, axboe@kernel.dk, agk@redhat.com, snitzer@kernel.org, dm-devel@redhat.com Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai3@huawei.com, yukuai1@huaweicloud.com, yi.zhang@huawei.com Subject: [PATCH v3 08/10] block: fix use after free for bd_holder_dir Date: Tue, 15 Nov 2022 22:10:52 +0800 Message-Id: <20221115141054.1051801-9-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20221115141054.1051801-1-yukuai1@huaweicloud.com> References: <20221115141054.1051801-1-yukuai1@huaweicloud.com> MIME-Version: 1.0 X-CM-TRANSID: gCh0CgBni9jnmHNjrPFIAg--.61645S12 X-Coremail-Antispam: 1UD129KBjvJXoW7tr1rGFyxAFWxAFy3Ar1DKFg_yoW8KFWUpF Z0gFyrKry8GrsrZrsrt347XFWjg3W8W3W8AFW29F4I9rZxArsI9r1xAFy7WF1xKrWIvF4q qF1UX3yFvF10kFDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPF14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JF0E3s1l82xGYI kIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2 z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F 4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq 3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7 IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4U M4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2 kIc2xKxwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E 14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIx kGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUCVW8JwCI42IY6xIIjxv20xvEc7CjxVAF wI0_Cr0_Gr1UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJV W8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjfUOBTY UUUUU X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: Yu Kuai Currently, the caller of bd_link_disk_holer() get 'bdev' by blkdev_get_by_dev(), which will look up 'bdev' by inode number 'dev'. Howerver, it's possible that del_gendisk() can be called currently, and 'bd_holder_dir' can be freed before bd_link_disk_holer() access it, thus use after free is triggered. t1: t2: bdev = blkdev_get_by_dev del_gendisk kobject_put(bd_holder_dir) kobject_free() bd_link_disk_holder Fix the problem by checking disk is still live and grabbing a reference to 'bd_holder_dir' first in bd_link_disk_holder(). Signed-off-by: Yu Kuai Reviewed-by: Christoph Hellwig --- block/holder.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) diff --git a/block/holder.c b/block/holder.c index dd9327b43ce0..c8e462053f49 100644 --- a/block/holder.c +++ b/block/holder.c @@ -65,12 +65,24 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) if (WARN_ON_ONCE(!disk->slave_dir)) return -EINVAL; - mutex_lock(&disk->open_mutex); + /* + * del_gendisk drops the initial reference to bd_holder_dir, so we + * need to keep our own here to allow for cleanup past that point. + */ + mutex_lock(&bdev->bd_disk->open_mutex); + if (!disk_live(bdev->bd_disk)) { + mutex_unlock(&bdev->bd_disk->open_mutex); + return -ENODEV; + } + kobject_get(bdev->bd_holder_dir); + mutex_unlock(&bdev->bd_disk->open_mutex); + mutex_lock(&disk->open_mutex); WARN_ON_ONCE(!bdev->bd_holder); holder = bd_find_holder_disk(bdev, disk); if (holder) { + kobject_put(bdev->bd_holder_dir); holder->refcnt++; goto out_unlock; } @@ -92,11 +104,6 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) goto out_del_symlink; list_add(&holder->list, &disk->slave_bdevs); - /* - * del_gendisk drops the initial reference to bd_holder_dir, so we need - * to keep our own here to allow for cleanup past that point. - */ - kobject_get(bdev->bd_holder_dir); mutex_unlock(&disk->open_mutex); return 0; @@ -106,6 +113,8 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) kfree(holder); out_unlock: mutex_unlock(&disk->open_mutex); + if (ret) + kobject_put(bdev->bd_holder_dir); return ret; } EXPORT_SYMBOL_GPL(bd_link_disk_holder);