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authorAnand Jain <anand.jain@oracle.com>2018-08-06 13:12:37 +0300
committerDavid Sterba <dsterba@suse.com>2018-08-23 18:37:27 +0300
commit801660b040d132f67fac6a95910ad307c5929b49 (patch)
treea179695d4720b1f61d2f8f6bb87c7bacaabf81b3 /fs
parenta5b7f4295eeae8b05ca91f6d145cd8773b08de9e (diff)
downloadlinux-801660b040d132f67fac6a95910ad307c5929b49.tar.xz
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 <lufq.fnst@cn.fujitsu.com> Tested-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com> Signed-off-by: Anand Jain <anand.jain@oracle.com> Reviewed-by: David Sterba <dsterba@suse.com> [ update changelog ] Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/volumes.c7
1 files changed, 6 insertions, 1 deletions
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) {