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Yuqi Xu 3acdd44385 tipc: destroy topsrv workqueues before closing connections
tipc_topsrv_stop() closed subscriber connections while the topology
server's send and receive workqueues were still running. Socket
callbacks and subscription events could then queue more work, and
in-flight send/recv work could drop the last connection reference
during the conn_idr walk.

That race produced several teardown failures: refcount_t addition on
0 from conn_get() on a connection whose release was blocked on
idr_lock, a subsequent use-after-free in tipc_conn_close(),
queue_work() on an already destroyed workqueue from the listener
data-ready callback, and an RCU stall in tipc_topsrv_exit_net()
while the walk spun under idr_lock.

Clear srv->listener under idr_lock so it acts as a shutdown flag,
skip queue_work() once it is NULL, destroy the workqueues to flush
in-flight work, and only then close the remaining connections.
Refuse tipc_conn_lookup() after that flag is cleared, and drop
idr_lock when the teardown walk finds no connection, so an
in-flight subscription event cannot pin idr_in_use while the
walk holds the lock.

v3 supersedes the narrower in-thread diff Tung Quang Nguyen
posted on 2026-09-23. It keeps his teardown order and adds the
lookup refusal and the empty-idr unlock.

Fixes: c5fa7b3cf3 ("tipc: introduce new TIPC server infrastructure")
Cc: [email protected]
Reported-by: Vega <[email protected]>
Assisted-by: LLM
Signed-off-by: Yuqi Xu <[email protected]>
Reviewed-by: Ren Wei <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
2026-10-02 08:20:15 +01:00
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2026-06-15 12:50:29 -07:00
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