ocfs2: synchronize heartbeat callbacks with o2net teardown

Patch series "ocfs2: harden heartbeat teardown races".

This series fixes two OCFS2 heartbeat/o2net teardown races found by
KASAN.


This patch (of 2):

Heartbeat callbacks stay registered while configfs local-node teardown
enters o2net_stop_listening().  A node-down event can still run through
o2net_disconnect_node() and o2net_set_nn_state() while teardown is
destroying o2net_wq, so the later queue/flush operations can hit a dead
workqueue.  KASAN has caught this as a slab-use-after-free in
__queue_work() with the call chain:

KASAN slab-use-after-free in __queue_work+0x56/0xa90
Read of size 4
Call trace:
  dump_stack_lvl+0x66/0xa0
  print_report+0xce/0x630
  __queue_work+0x56/0xa90
  srso_alias_return_thunk+0x5/0xfbef5
  __virt_addr_valid+0x19f/0x330
  kasan_report+0xe0/0x110
  __queue_delayed_work+0x58/0x1e0
  queue_delayed_work_on+0xb4/0xc0
  o2net_set_nn_state+0x467/0x840
  o2net_disconnect_node+0x7b/0xe0
  o2net_hb_node_down_cb+0x54/0x60
  o2hb_run_event_list+0x236/0x2d0
  o2hb_check_slot+0xad4/0xbc0
  lock_release+0xc8/0x290
  o2hb_check_slot+0x9ea/0xbc0
  trace_hardirqs_on+0x18/0x130
  o2hb_do_disk_heartbeat+0x646/0xb30 (fs/ocfs2/cluster/heartbeat.c:1079)
  __lock_acquire+0x466/0x2260
  lockdep_hardirqs_on_prepare+0xea/0x1a0
  ktime_get_with_offset+0xe9/0x230
  o2hb_thread+0x14e/0x770
  kthread+0x1ad/0x1f0
  ret_from_fork+0x3c9/0x540
  __switch_to+0x2e9/0x730
  ret_from_fork_asm+0x1a/0x30
Allocated by task stack:
  kasan_save_stack+0x33/0x60
  kasan_save_track+0x14/0x30
  __kasan_kmalloc+0xaa/0xb0
  __kmalloc_noprof+0x292/0x760
  __alloc_workqueue+0x736/0xc60
  alloc_workqueue_noprof+0xb1/0x110
  o2net_start_listening+0xe5/0x430
  o2nm_node_local_store+0x184/0x310
  configfs_write_iter+0x18a/0x210
  vfs_write+0x469/0x810
  ksys_write+0xd2/0x170
  do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87)
  entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task stack:
  kasan_save_stack+0x33/0x60
  kasan_save_track+0x14/0x30
  kasan_save_free_info+0x3b/0x60
  __kasan_slab_free+0x5f/0x80
  kfree+0x313/0x590
  rcu_core+0x4f4/0x1320
  handle_softirqs+0x156/0x660

queue_delayed_work_on
o2net_set_nn_state
o2net_disconnect_node
o2net_hb_node_down_cb
o2hb_run_event_list

Keep heartbeat callbacks registered so quorum state still tracks node
state, but stop them from driving o2net reconnect/disconnect work once
local teardown starts. Mark the transport offline before destroying
o2net_wq, wait for any in-flight heartbeat callback to finish, and delay
bring-up replay until the new local node is published through
o2nm_this_node().

The replay also has to stay serialized with heartbeat callback delivery.
Otherwise a live-node snapshot can be copied, a real hb_down callback
can install -ENOTCONN for a peer, and the stale replay can call
o2net_hb_node_up() for that same peer and queue reconnect work even
though heartbeat is already down.

The buggy scenario involves two paths, with each column showing the order
within that path:

local-node teardown:                 heartbeat node-down callback:
1. configfs local-off enters         1. o2hb_run_event_list() invokes
   o2net_stop_listening().              o2net_hb_node_down_cb().
2. teardown heads for                2. the callback reaches
   destroy_workqueue(o2net_wq).         o2net_disconnect_node() and
                                        o2net_set_nn_state().
3. teardown destroys and NULLs       3. the callback flushes or queues
   o2net_wq.                            work through o2net_wq.

Link: https://lore.kernel.org/20260624095310.763763-1-zzzccc427@gmail.com
Link: https://lore.kernel.org/20260624095310.763763-2-zzzccc427@gmail.com
Fixes: 98211489d414 ("[PATCH] OCFS2: The Second Oracle Cluster Filesystem")
Signed-off-by: Cen Zhang <zzzccc427@gmail.com>
Assisted-by: Codex:gpt-5.5
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Heming Zhao <heming.zhao@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Jun Piao <piaojun@huawei.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Mark Fasheh <mark@fasheh.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

0 files changed, 0 insertions, 0 deletions