From 801660b040d132f67fac6a95910ad307c5929b49 Mon Sep 17 00:00:00 2001 From: Anand Jain Date: Mon, 6 Aug 2018 18:12:37 +0800 Subject: btrfs: btrfs_shrink_device should call commit transaction at the end Test case btrfs/164 reports use-after-free: [ 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 resized device 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 transactio ncommit. It goes through the fs_devices::resized_devices in btrfs_update_commit_device_size and leads to use-after-free. Fix this by making sure btrfs_shrink_device calls the last needed btrfs_commit_transaction before the return. This is consistent with what the grow counterpart does and this makes sure the on-disk state is persistent when the function returns. Reported-by: Lu Fengqi Tested-by: Lu Fengqi Signed-off-by: Anand Jain Reviewed-by: David Sterba [ update changelog ] Signed-off-by: David Sterba --- fs/btrfs/volumes.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'fs') 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 @@ again: /* 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) { -- cgit v1.2.3