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net/smc: add fallback check to connect()

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FASTOPEN setsockopt() or sendmsg() may switch the SMC socket to fallback
mode. Once fallback mode is active, the native TCP socket functions are
called. Nevertheless there is a small race window, when FASTOPEN
setsockopt/sendmsg runs in parallel to a connect(), and switch the
socket into fallback mode before connect() takes the sock lock.
Make sure the SMC-specific connect setup is omitted in this case.

This way a syzbot-reported refcount problem is fixed, triggered by
different threads running non-blocking connect() and FASTOPEN_KEY
setsockopt.

Reported-by: syzbot+96d3f9ff6a86d37e44c8@syzkaller.appspotmail.com
Fixes: 6d6dd528d5 ("net/smc: fix refcount non-blocking connect() -part 2")
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
This commit is contained in:
Ursula Braun 2019-12-12 22:35:58 +01:00 committed by Jakub Kicinski
parent 9b2079c046
commit 86434744fe
1 changed files with 8 additions and 6 deletions
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12
net/smc/af_smc.c
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@ -857,6 +857,8 @@ static int smc_connect(struct socket *sock, struct sockaddr *addr,
goto out;
sock_hold(&smc->sk); /* sock put in passive closing */
if (smc->use_fallback)
goto out;
if (flags & O_NONBLOCK) {
if (schedule_work(&smc->connect_work))
smc->connect_nonblock = 1;
@ -1721,8 +1723,6 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
sk->sk_err = smc->clcsock->sk->sk_err;
sk->sk_error_report(sk);
}
if (rc)
return rc;
if (optlen < sizeof(int))
return -EINVAL;
@ -1730,6 +1730,8 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
return -EFAULT;
lock_sock(sk);
if (rc || smc->use_fallback)
goto out;
switch (optname) {
case TCP_ULP:
case TCP_FASTOPEN:
@ -1741,7 +1743,6 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
smc_switch_to_fallback(smc);
smc->fallback_rsn = SMC_CLC_DECL_OPTUNSUPP;
} else {
if (!smc->use_fallback)
rc = -EINVAL;
}
break;
@ -1749,7 +1750,7 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
if (sk->sk_state != SMC_INIT &&
sk->sk_state != SMC_LISTEN &&
sk->sk_state != SMC_CLOSED) {
if (val && !smc->use_fallback)
if (val)
mod_delayed_work(system_wq, &smc->conn.tx_work,
0);
}
@ -1758,7 +1759,7 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
if (sk->sk_state != SMC_INIT &&
sk->sk_state != SMC_LISTEN &&
sk->sk_state != SMC_CLOSED) {
if (!val && !smc->use_fallback)
if (!val)
mod_delayed_work(system_wq, &smc->conn.tx_work,
0);
}
@ -1769,6 +1770,7 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
default:
break;
}
out:
release_sock(sk);
return rc;