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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 5EFA9C47E48 for ; Thu, 15 Jul 2021 10:34:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4962361158 for ; Thu, 15 Jul 2021 10:34:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241429AbhGOKh2 (ORCPT ); Thu, 15 Jul 2021 06:37:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55498 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231670AbhGOKh0 (ORCPT ); Thu, 15 Jul 2021 06:37:26 -0400 Received: from mail-pj1-x1035.google.com (mail-pj1-x1035.google.com [IPv6:2607:f8b0:4864:20::1035]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7D07DC06175F; Thu, 15 Jul 2021 03:34:32 -0700 (PDT) Received: by mail-pj1-x1035.google.com with SMTP id h1-20020a17090a3d01b0290172d33bb8bcso5918749pjc.0; Thu, 15 Jul 2021 03:34:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=+oSd5AIwHXyRxmbXI7YN1Do3jrBN/ZwcUGcPjvgZeFk=; b=AFHnbrvTfgXatGFDpeKuSk4yYxFCvxAArkKWMB2xhrzPriZ/ItDVwlf7rzN6cGdXKS aMvgfdXg19XYmqFFhWHPqLHctEIDlFvgNxMAItXD8hJQNgnZMOHUiIcbjEzMmp9/+7Fy xWD8qhbnLO+NFEyMxNiPj2PuX2wtqXQTTcmSx18tbeTcKkZBj8DJ9ZWe0DbhX/xavYan LeBhysNvsvj3U/jrYtUvwi0Zj2D/vMWyI7hdstrBLS5uTMeYaOGNOUDM1EMRAtASVbgP WvLSIXnwdZoHmrVNYWqAyk1bWRwcXU1XHdxAQO4Q8FhtLU52cdQL3c1z1Rt431Wg+a+L ux2g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=+oSd5AIwHXyRxmbXI7YN1Do3jrBN/ZwcUGcPjvgZeFk=; b=Jlz9yRREoEOb9ZIA89kf/RtNhqvNZJNJNUxRVnT3aCgid0RfbgtpfS87rO2/D1yMxS STMTqawEvxyTK++XF1mm3WOfO3c1/aqYO3TiRio9TesH7jz9Ppdrad91FqYJrUN50thC 6gM8HZOVykr/gpi/HW7VFaHXHC/MzMRQW6SNAaZ66Rf6c//qQxJmyClHufrgesY0eF1f ct9ZL6L2PU2vOcT0dUyFj8dxWxkisROU1YS2ZHjnYVjG2joffezOCOgpcfj4qFKZerud a5CgvWFWbCtnB5+XCLfteL+cnZYNnK49XHThfS8siTu4ZgL1dDj4T4xZFJ7Qs+2nBlZo DJVw== X-Gm-Message-State: AOAM530IF0a5/NERFKwswMHYlxide7v0YBm4K2SbSTTIdjUrtNHFDwtl yclNNX/euC1be1cknhkpUUA= X-Google-Smtp-Source: ABdhPJzsgVuM1EhE0Bt1tm9UkzYH3XoF5+771CCc0YfNyBorSFfKh1zma+esEJdf3zhFYWz2Y4Kgpw== X-Received: by 2002:a17:90a:8e82:: with SMTP id f2mr9659205pjo.177.1626345272037; Thu, 15 Jul 2021 03:34:32 -0700 (PDT) Received: from localhost.localdomain ([118.200.190.93]) by smtp.gmail.com with ESMTPSA id e18sm6059326pfc.85.2021.07.15.03.34.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Jul 2021 03:34:31 -0700 (PDT) From: Desmond Cheong Zhi Xi To: clm@fb.com, josef@toxicpanda.com, dsterba@suse.com Cc: Desmond Cheong Zhi Xi , anand.jain@oracle.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, gregkh@linuxfoundation.org, linux-kernel-mentees@lists.linuxfoundation.org, syzbot+a70e2ad0879f160b9217@syzkaller.appspotmail.com Subject: [PATCH] btrfs: fix rw device counting in __btrfs_free_extra_devids Date: Thu, 15 Jul 2021 18:34:03 +0800 Message-Id: <20210715103403.176695-1-desmondcheongzx@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Syzbot reports a warning in close_fs_devices that happens because fs_devices->rw_devices is not 0 after calling btrfs_close_one_device on each device. This happens when a writeable device is removed in __btrfs_free_extra_devids, but the rw device count is not decremented accordingly. So when close_fs_devices is called, the removed device is still counted and we get an off by 1 error. Here is one call trace that was observed: btrfs_mount_root(): btrfs_scan_one_device(): device_list_add(); <---------------- device added btrfs_open_devices(): open_fs_devices(): btrfs_open_one_device(); <-------- rw device count ++ btrfs_fill_super(): open_ctree(): btrfs_free_extra_devids(): __btrfs_free_extra_devids(); <--- device removed fail_tree_roots: btrfs_close_devices(): close_fs_devices(); <------- rw device count off by 1 Fixes: cf89af146b7e ("btrfs: dev-replace: fail mount if we don't have replace item with target device") Reported-by: syzbot+a70e2ad0879f160b9217@syzkaller.appspotmail.com Tested-by: syzbot+a70e2ad0879f160b9217@syzkaller.appspotmail.com Signed-off-by: Desmond Cheong Zhi Xi --- fs/btrfs/volumes.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 807502cd6510..916c25371658 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1078,6 +1078,7 @@ static void __btrfs_free_extra_devids(struct btrfs_fs_devices *fs_devices, if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) { list_del_init(&device->dev_alloc_list); clear_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state); + fs_devices->rw_devices--; } list_del_init(&device->dev_list); fs_devices->num_devices--; -- 2.25.1