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Mon, 07 Sep 2026 11:35:55 -0700 (PDT) Date: Tue, 8 Sep 2026 03:35:51 +0900 From: Hyunwoo Kim To: Michal Luczaj , Stefano Garzarella Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, leonardi@redhat.com, bobbyeshleman@meta.com, stefanha@redhat.com, mst@redhat.com, virtualization@lists.linux.dev, netdev@vger.kernel.org, imv4bel@gmail.com Subject: Re: [PATCH net] vsock: do not reset a socket in connect() once it has connected Message-ID: References: <218226a4-38e6-4a16-a660-6c1bb92f9f96@rbox.co> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Aug 19, 2026 at 10:54:38AM +0200, Stefano Garzarella wrote: > On Mon, Aug 17, 2026 at 12:29:11AM +0200, Michal Luczaj wrote: > > On 8/14/26 03:45, Hyunwoo Kim wrote: > > > On Thu, Aug 13, 2026 at 11:42:17AM +0200, Michal Luczaj wrote: > > > > On 8/12/26 22:13, Hyunwoo Kim wrote: > > > > > commit 002541ef650b ("vsock: Ignore signal/timeout on connect() if > > > > > already established") stopped connect() from resetting an established > > > > > socket. The check only looks at whether sk_state is TCP_ESTABLISHED at > > > > > that moment, and the state can change while connect() sleeps. > > > > > > > > I guess this makes my fix incomplete. "Fixes: 002541ef650b"? > > > > > > It is incomplete, yes. But this has been triggerable since d021c344051a, so > > > I'd keep Fixes: d021c344051a. > > > > OK, I get it. > > > > > > > A peer RST moves the socket to TCP_CLOSING, and it is not removed from > > > > > vsock_connected_table on that path. connect() then wakes up, fails the > > > > > check, and resets a socket that had actually connected to TCP_CLOSE and > > > > > SS_UNCONNECTED. > > > > > > > > Thanks for the details. Do I get it right: connect() misses the fact that > > > > socket might have already transitioned TCP_ESTABLISHED -> TCP_CLOSING > > > > during schedule_timeout()? > > > > > > Yes, that's it. > > > > > > > > > > > How about: > > > > > > > > diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c > > > > index 622dbd046799..39c42ef016c3 100644 > > > > --- a/net/vmw_vsock/af_vsock.c > > > > +++ b/net/vmw_vsock/af_vsock.c > > > > @@ -1807,15 +1807,18 @@ static int vsock_connect(struct socket *sock, struct sockaddr_unsized *addr, > > > > timeout = schedule_timeout(timeout); > > > > lock_sock(sk); > > > > > > > > - /* Connection established. Whatever happens to socket once we > > > > + /* Connection (has been) established. Whatever happens to socket once we > > > > * release it, that's not connect()'s concern. No need to go > > > > * into signal and timeout handling. Call it a day. > > > > * > > > > * Note that allowing to "reset" an already established socket > > > > * here is racy and insecure. > > > > */ > > > > - if (sk->sk_state == TCP_ESTABLISHED) > > > > - break; > > > > + if (sk->sk_state == TCP_ESTABLISHED || > > > > + sk->sk_state == TCP_CLOSING) { > > > > + err = -sk->sk_err; > > > > + goto out_wait; > > > > + } > > > > > > > > /* If connection was _not_ established and a signal/timeout came > > > > * to be, we want the socket's state reset. User space may want > > > > > > > > ? > > > > > > Yes, I like it better than mine. I confirmed it fixes the issue. > > > > Great, thanks. > > > > > If you don't mind, would you take the patch from here? > > > > Sure, no problem. > > > > Stefano, does this look good to you? > > Yep, thanks for helping here! > > My only doubt is if it makes sense to leave the `break` there, and add a > similar check before resetting the socket, I mean something like this: > > err = sock_error(sk); > if (err && sk->sk_state != TCP_ESTABLISHED && > sk->sk_state != TCP_CLOSING)) { > sk->sk_state = TCP_CLOSE; > sock->state = SS_UNCONNECTED; > } > > Just to be a bit more defensive, but I don't have a strong opinion, your > version is also fine. > > > And should any sk_err be consumed > > here, too? (`err = sock_error(sk)` instead of `err = -sk->sk_err`) > > I'd stay with sock_error() to consume the error if it makes sense also for > you. > > Thanks, > Stefano > Gentle ping. I'd appreciate an update on where this stands. Best regards, Hyunwoo Kim