From: Ursula Braun ubraun@linux.ibm.com
[ Upstream commit 8204df72bea1a7d83d0777add6da98a41dfbdc34 ]
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 ubraun@linux.ibm.com Signed-off-by: Karsten Graul kgraul@linux.ibm.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 @@ -1731,7 +1731,7 @@ static int smc_setsockopt(struct socket 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 {