4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ursula Braun <ubraun@xxxxxxxxxxxxx> [ Upstream commit 784813aed6ba24a1f24e7e11d9d0f208cee37a7d ] 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@xxxxxxxxxxxxx> Reported-by: syzbot+03faa2dc16b8b64be396@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/smc/af_smc.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) --- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -1165,13 +1165,15 @@ static __poll_t smc_poll(struct file *fi /* 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;
