| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.17 192/219] btrfs: fix root ref counts in error handling in btrfs_get_root_ref | Date | Mon, 18 Apr 2022 14:12:41 +0200 |
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From: Jia-Ju Bai <baijiaju1990@gmail.com>
commit 168a2f776b9762f4021421008512dd7ab7474df1 upstream.
In btrfs_get_root_ref(), when btrfs_insert_fs_root() fails, btrfs_put_root() can happen for two reasons:
- the root already exists in the tree, in that case it returns the reference obtained in btrfs_lookup_fs_root()
- another error so the cleanup is done in the fail label
Calling btrfs_put_root() unconditionally would lead to double decrement of the root reference possibly freeing it in the second case.
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn> Fixes: bc44d7c4b2b1 ("btrfs: push btrfs_grab_fs_root into btrfs_get_fs_root") CC: stable@vger.kernel.org # 5.10+ Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- fs/btrfs/disk-io.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1826,9 +1826,10 @@ again: ret = btrfs_insert_fs_root(fs_info, root); if (ret) { - btrfs_put_root(root); - if (ret == -EEXIST) + if (ret == -EEXIST) { + btrfs_put_root(root); goto again; + } goto fail; } return root;
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