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;