From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([59.151.112.132]:10872 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S932552AbaICNeQ (ORCPT ); Wed, 3 Sep 2014 09:34:16 -0400 Received: from G08CNEXCHPEKD01.g08.fujitsu.local (localhost.localdomain [127.0.0.1]) by edo.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id s83DYDLT006681 for ; Wed, 3 Sep 2014 21:34:13 +0800 From: Miao Xie To: Subject: [PATCH 13/18] Btrfs: fix unprotected device list access when cloning fs devices Date: Wed, 3 Sep 2014 21:35:42 +0800 Message-ID: <1409751347-5296-13-git-send-email-miaox@cn.fujitsu.com> In-Reply-To: <1409751347-5296-1-git-send-email-miaox@cn.fujitsu.com> References: <1409751347-5296-1-git-send-email-miaox@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-btrfs-owner@vger.kernel.org List-ID: We can build a new filesystem based a seed filesystem, and we need clone the fs devices when we open the new filesystem. But someone might clear the seed flag of the seed filesystem, then mount that filesystem and remove some device. If we mount the new filesystem, we might access a device list which was being changed when we clone the fs devices. Fix it. Signed-off-by: Miao Xie --- fs/btrfs/volumes.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 357f911..f0173b1 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -583,6 +583,7 @@ static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig) if (IS_ERR(fs_devices)) return fs_devices; + mutex_lock(&orig->device_list_mutex); fs_devices->total_devices = orig->total_devices; /* We have held the volume lock, it is safe to get the devices. */ @@ -611,8 +612,10 @@ static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig) device->fs_devices = fs_devices; fs_devices->num_devices++; } + mutex_unlock(&orig->device_list_mutex); return fs_devices; error: + mutex_unlock(&orig->device_list_mutex); free_fs_devices(fs_devices); return ERR_PTR(-ENOMEM); } -- 1.9.3