net/smc: avoid fallback in case of non-blocking connect (cd206360) · Commits · 戴 / test

FASTOPEN is not possible with SMC. sendmsg() with msg_flag MSG_FASTOPEN triggers a fallback to TCP if the socket is in state SMC_INIT. But if a nonblocking connect is already started, fallback to TCP is no longer possible, even though the socket may still be in state SMC_INIT. And if a nonblocking connect is already started, a listen() call does not make sense. Reported-by:

<syzbot+bd8cc73d665590a1fcad@syzkaller.appspotmail.com> Fixes: ("net/smc: nonblocking connect rework") Signed-off-by:

Ursula Braun <ubraun@linux.ibm.com> Signed-off-by:

Karsten Graul <kgraul@linux.ibm.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/smc/af_smc.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -263,7 +263,7 @@ static int smc_bind(struct socket sock, struct sockaddr uaddr,

		/* Check if socket is already active */
		rc = -EINVAL;
		if (sk->sk_state != SMC_INIT)
		if (sk->sk_state != SMC_INIT \|\| smc->connect_nonblock)
		goto out_rel;

		smc->clcsock->sk->sk_reuse = sk->sk_reuse;
		@@ -1390,7 +1390,8 @@ static int smc_listen(struct socket *sock, int backlog)
		lock_sock(sk);

		rc = -EINVAL;
		if ((sk->sk_state != SMC_INIT) && (sk->sk_state != SMC_LISTEN))
		if ((sk->sk_state != SMC_INIT && sk->sk_state != SMC_LISTEN) \|\|
		smc->connect_nonblock)
		goto out;

		rc = 0;
		@@ -1518,7 +1519,7 @@ static int smc_sendmsg(struct socket sock, struct msghdr msg, size_t len)
		goto out;

		if (msg->msg_flags & MSG_FASTOPEN) {
		if (sk->sk_state == SMC_INIT) {
		if (sk->sk_state == SMC_INIT && !smc->connect_nonblock) {
		smc_switch_to_fallback(smc);
		smc->fallback_rsn = SMC_CLC_DECL_OPTUNSUPP;
		} else {

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