Re: [syzbot] [bpf?] [sctp?] [tipc?] INFO: rcu detected stall in sock_close (5)

[Hillf Danton]

> Date: Wed, 22 Jul 2026 08:42:25 -0700
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    248951ddc14d Merge tag 'hwmon-for-v7.2-rc5' of git://git.k..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=15080ab9580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=98da55a882774dfe
> dashboard link: https://syzkaller.appspot.com/bug?extid=9a29e1dba699b6f46a03
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=165d9746580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15ba2ab9580000

#syz test

--- x/net/tipc/socket.c
+++ y/net/tipc/socket.c
@@ -2489,7 +2489,10 @@ void tipc_sk_rcv(struct net *net, struct
 	struct tipc_sock *tsk;
 	struct sock *sk;
 	struct sk_buff *skb;
+	static int nogo = 0;
 
+	if (nogo)
+		return;
 	__skb_queue_head_init(&xmitq);
 	while (skb_queue_len(inputq)) {
 		dport = tipc_skb_peek_port(inputq, dport);
@@ -2498,7 +2501,9 @@ void tipc_sk_rcv(struct net *net, struct
 		if (likely(tsk)) {
 			sk = &tsk->sk;
 			if (likely(spin_trylock_bh(&sk->sk_lock.slock))) {
+				nogo = 1;
 				tipc_sk_enqueue(inputq, sk, dport, &xmitq);
+				nogo = 0;
 				spin_unlock_bh(&sk->sk_lock.slock);
 			}
 			/* Send pending response/rejected messages, if any */
--