From: Ursula Braun Date: Fri, 15 Nov 2019 12:39:30 +0100 Subject: net/smc: fix fastopen for non-blocking connect() Git-commit: 8204df72bea1a7d83d0777add6da98a41dfbdc34 Patch-mainline: v5.4-rc8 References: git-fixes 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 cd2063604ea6 ("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: e1bbdd570474 ("net/smc: reduce sock_put() for fallback sockets") Signed-off-by: Ursula Braun Signed-off-by: Karsten Graul Signed-off-by: David S. Miller Acked-by: Petr Tesarik --- net/smc/af_smc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -1737,7 +1737,7 @@ static int smc_setsockopt(struct socket case TCP_FASTOPEN: case TCP_FASTOPEN_CONNECT: /* 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 {