From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp2120.oracle.com ([156.151.31.85]:55470 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727700AbeHFMR2 (ORCPT ); Mon, 6 Aug 2018 08:17:28 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w76A8niI024537 for ; Mon, 6 Aug 2018 10:09:06 GMT Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by userp2120.oracle.com with ESMTP id 2kn4spm39s-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Mon, 06 Aug 2018 10:09:06 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id w76A95Ga028746 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Mon, 6 Aug 2018 10:09:05 GMT Received: from abhmp0007.oracle.com (abhmp0007.oracle.com [141.146.116.13]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id w76A94lB006227 for ; Mon, 6 Aug 2018 10:09:05 GMT From: Anand Jain To: linux-btrfs@vger.kernel.org Subject: [PATCH v2] btrfs: btrfs_shrink_device should call commit transaction Date: Mon, 6 Aug 2018 18:12:37 +0800 Message-Id: <20180806101237.20507-1-anand.jain@oracle.com> In-Reply-To: <20180725132727.642-1-anand.jain@oracle.com> References: <20180725132727.642-1-anand.jain@oracle.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: test case btrfs/164 reported UAF.. [ 6712.084324] general protection fault: 0000 [#1] PREEMPT SMP :: [ 6712.195423] btrfs_update_commit_device_size+0x75/0xf0 [btrfs] [ 6712.201424] btrfs_commit_transaction+0x57d/0xa90 [btrfs] [ 6712.206999] btrfs_rm_device+0x627/0x850 [btrfs] [ 6712.211800] btrfs_ioctl+0x2b03/0x3120 [btrfs] :: reason for this is that btrfs_shrink_device() adds the device resized to the fs_devices::resized_devices after it has called the last commit transaction. So the list fs_devices::resized_devices is not empty when btrfs_shrink_device() returns. Now the parent function btrfs_rm_device() calls btrfs_close_bdev(device); call_rcu(&device->rcu, free_device_rcu); and then does the commit transaction. The commit transaction goes through the fs_devices::resized_devices in btrfs_update_commit_device_size() and leads to UAF. Fix this by making sure btrfs_shrink_device() calls the last needed btrfs_commit_transaction() before the return. Reported-by: Lu Fengqi Signed-off-by: Anand Jain Tested-by: Lu Fengqi --- v1->v2: cleanup the dirty and new meta block group before ending the transaction when btrfs_update_device fails. fs/btrfs/volumes.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index da86706123ff..f4405e430da6 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -4491,7 +4491,12 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size) /* Now btrfs_update_device() will change the on-disk size. */ ret = btrfs_update_device(trans, device); - btrfs_end_transaction(trans); + if (ret < 0) { + btrfs_abort_transaction(trans, ret); + btrfs_end_transaction(trans); + } else { + ret = btrfs_commit_transaction(trans); + } done: btrfs_free_path(path); if (ret) { -- 2.7.0