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net/smc: restrict non-blocking connect finish

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The smc_poll code tries to finish connect() if the socket is in
state SMC_INIT and polling of the internal CLC-socket returns with
EPOLLOUT. This makes sense for a select/poll call following a connect
call, but not without preceding connect().
With this patch smc_poll starts connect logic only, if the CLC-socket
is no longer in its initial state TCP_CLOSE.

In addition, a poll error on the internal CLC-socket is always
propagated to the SMC socket.

With this patch the code path mentioned by syzbot
https://syzkaller.appspot.com/bug?extid=03faa2dc16b8b64be396
is no longer possible.

Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Reported-by: syzbot+03faa2dc16b8b64be396@syzkaller.appspotmail.com
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ursula Braun 2018-05-02 16:53:56 +02:00 committed by David S. Miller
parent af3e0fcf78
commit 784813aed6
1 changed files with 8 additions and 6 deletions
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14
net/smc/af_smc.c
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@ -1166,13 +1166,15 @@ static __poll_t smc_poll(struct file *file, struct socket *sock,
/* delegate to CLC child sock */
release_sock(sk);
mask = smc->clcsock->ops->poll(file, smc->clcsock, wait);
/* if non-blocking connect finished ... */
lock_sock(sk);
if ((sk->sk_state == SMC_INIT) && (mask & EPOLLOUT)) {
sk->sk_err = smc->clcsock->sk->sk_err;
if (sk->sk_err) {
mask |= EPOLLERR;
} else {
sk->sk_err = smc->clcsock->sk->sk_err;
if (sk->sk_err) {
mask |= EPOLLERR;
} else {
/* if non-blocking connect finished ... */
if (sk->sk_state == SMC_INIT &&
mask & EPOLLOUT &&
smc->clcsock->sk->sk_state != TCP_CLOSE) {
rc = smc_connect_rdma(smc);
if (rc < 0)
mask |= EPOLLERR;