Re: [syzbot] Re: [syzbot] [rdma?] [s390?] [net?] KASAN: null-ptr-deref Read in smc_tcp_syn_recv_sock

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Subject: Re: [syzbot] [rdma?] [s390?] [net?] KASAN: null-ptr-deref Read in smc_tcp_syn_recv_sock
Author: richard120310@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 850925a8133c

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 3e6cb35baf25..41f8dcd734a6 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -127,6 +127,8 @@ static struct sock *smc_tcp_syn_recv_sock(const struct sock *sk,
 	struct sock *child;
 
 	smc = smc_clcsock_user_data(sk);
+	if (!smc)
+		goto drop;
 
 	if (READ_ONCE(sk->sk_ack_backlog) + atomic_read(&smc->queued_smc_hs) >
 				sk->sk_max_ack_backlog)