Commit 8204df72 authored Nov 15, 2019 by Ursula Braun Committed by David S. Miller Nov 16, 2019

net/smc: fix fastopen for non-blocking connect()



FASTOPEN does not work with SMC-sockets. Since SMC allows fallback to
TCP native during connection start, the FASTOPEN setsockopts trigger
this fallback, if the SMC-socket is still in state SMC_INIT.
But if a FASTOPEN setsockopt is called after a non-blocking connect(),
this is broken, and fallback does not make sense.
This change complements
commit cd206360 ("net/smc: avoid fallback in case of non-blocking connect")
and fixes the syzbot reported problem "WARNING in smc_unhash_sk".

Reported-by:  <syzbot+8488cc4cf1c9e09b8b86@syzkaller.appspotmail.com>
Fixes: e1bbdd57 ("net/smc: reduce sock_put() for fallback sockets")
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>

parent a36e629e

net/smc/af_smc.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1732,7 +1732,7 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
		case TCP_FASTOPEN_KEY:
		case TCP_FASTOPEN_NO_COOKIE:
		/* option not supported by SMC */
		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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