[PATCH v2 0/3] btrfs: fix a UAF where btrfs_root::dirty_list is freed but still referred

[Qu Wenruo <wqu@suse.com>]

The first patch is to make lock consistent when accessing
btrfs_root::dirty_list, btrfs_fs_info::dirty_cowonly_roots and
btrfs_transaction::switch_commits.

Normally it's not a big deal as the existing lock-holding callers are
also holding a trans handle, thus they can not race with transaction
committing.
But the last commit will change the cleanup timing, and Sashiko is not
happy with that, so make it more consistent and shut Sashiko up.

The second patch is an existing bug exposed by Sashiko, which also
affects the last UAF fix.

The last one is the final UAF fix for the bug reported by syzbot.

Qu Wenruo (3):
  btrfs: protect dirty_cowonly_roots, switch_commits and
    root->dirty_list
  btrfs: prevent use-after-free in btrfs_transaction::switch_commits
  btrfs: unlink btrfs_root::dirty_list during btrfs_put_root()

 fs/btrfs/disk-io.c         | 20 ++++++++++++++++++--
 fs/btrfs/free-space-tree.c |  4 ----
 fs/btrfs/qgroup.c          |  4 ----
 fs/btrfs/transaction.c     | 30 ++++++++++++++++++++++++++----
 4 files changed, 44 insertions(+), 14 deletions(-)

-- 
2.55.0