[PATCH net v2 1/2] tipc: stop the listener before draining connections

tipc_topsrv_stop() destroyed the receive workqueue while the listener
socket still had its data-ready callback and sk_user_data installed.
An incoming connection request could then queue srv->awork on the freed
workqueue from tipc_topsrv_listener_data_ready().

Reject new accepts, clear sk_user_data under sk_callback_lock and cancel
pending accept work before the workqueues are torn down.

Fixes: 0ef897be12b8 ("tipc: separate topology server listener socket from subcsriber sockets")
Cc: stable@vger.kernel.org
Reported-by: Vega <redacted>
Assisted-by: LLM
Signed-off-by: Yuqi Xu <redacted>
Reviewed-by: Ren Wei <redacted>
---
Changes in v2:
 - Rebased onto the current net/main tip; patch content unchanged.

 net/tipc/topsrv.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/net/tipc/topsrv.c b/net/tipc/topsrv.c
index af530c9ed840..908622a3d0fc 100644
--- a/net/tipc/topsrv.c
+++ b/net/tipc/topsrv.c

@@ -700,6 +700,15 @@ static void tipc_topsrv_stop(struct net *net)
 	struct tipc_conn *con;
 	int id;
 
+	spin_lock_bh(&srv->idr_lock);
+	srv->listener = NULL;
+	spin_unlock_bh(&srv->idr_lock);
+
+	write_lock_bh(&lsock->sk->sk_callback_lock);
+	lsock->sk->sk_user_data = NULL;
+	write_unlock_bh(&lsock->sk->sk_callback_lock);
+	cancel_work_sync(&srv->awork);
+
 	spin_lock_bh(&srv->idr_lock);
 	for (id = 0; srv->idr_in_use; id++) {
 		con = idr_find(&srv->conn_idr, id);

@@ -713,7 +722,6 @@ static void tipc_topsrv_stop(struct net *net)
 	}
 	__module_get(lsock->ops->owner);
 	__module_get(lsock->sk->sk_prot_creator->owner);
-	srv->listener = NULL;
 	spin_unlock_bh(&srv->idr_lock);
 
 	tipc_topsrv_work_stop(srv);

-- 
2.55.0