Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [Medium] vsock: connect() corrupts state and bytes_unsent on swept established socket --
commit 1f8c2b3f7e5cf0bf0bba26600e236377dd6b1fe3 Author: Bobby Eshleman <[email protected]> vsock: add a netlink command to assign the g2h device to a netns This commit introduces a vsock generic netlink family with VSOCK_CMD_DEV_NETNS_SET and VSOCK_CMD_DEV_NETNS_GET to assign the guest-to-host vsock device to a network namespace and query its assignment. Sockets that can no longer reach the device after an assignment are closed with ECONNRESET. Link: https://lore.kernel.org/all/20200427142518.uwssa6dtasrp3bfc@steredhat/ > diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c > index c9b28e34b1b3c..7140a3c708389 100644 > --- a/net/vmw_vsock/af_vsock.c > +++ b/net/vmw_vsock/af_vsock.c [ ... ] > @@ -742,8 +868,269 @@ bool vsock_find_cid(unsigned int cid) [ ... ] > +/* Close every connected socket of @t that can no longer reach the g2h > device. > + */ > +static void vsock_g2h_reset_unreachable(const struct vsock_transport *t) > +{ > + struct vsock_sock *vsk; > + unsigned int i = 0; > + struct sock *sk; > + bool reset; > + > + lockdep_assert_held(&vsock_g2h_assign_mutex); > + lockdep_assert_not_held(&vsock_register_mutex); > + > + /* lock_sock() cannot be taken under vsock_table_lock, so pick the > + * sockets one at a time, then recheck each under both locks. > + */ > + while ((sk = vsock_next_connected_socket(t, &i, > + vsock_g2h_should_reset))) { > + vsk = vsock_sk(sk); > + > + lock_sock(sk); > + > + reset = false; > + spin_lock_bh(&vsock_table_lock); > + /* It may have been closed since we dropped the table lock. */ > + if (__vsock_in_connected_table(vsk) && vsk->transport == t && > + vsock_g2h_should_reset(vsk)) { > + __vsock_remove_connected(vsk); > + reset = true; > + } > + spin_unlock_bh(&vsock_table_lock); > + > + if (reset) { > + sock_set_flag(sk, SOCK_DONE); > + WRITE_ONCE(vsk->peer_shutdown, SHUTDOWN_MASK); > + sk->sk_state = TCP_CLOSE; > + sk->sk_err = ECONNRESET; > + sk_error_report(sk); > + } > + > + release_sock(sk); > + sock_put(sk); > + } > +} [ ... ] > @@ -1705,6 +2093,16 @@ static void vsock_connect_timeout(struct work_struct > *work) > sock_put(sk); > } > > +/* Avoid breaking the socket when another thread has changed its sock->state > + * while we were asleep. > + */ > +static void vsock_connect_close(struct socket *sock) > +{ > + sock->sk->sk_state = TCP_CLOSE; > + if (sock->state == SS_CONNECTING) > + sock->state = SS_UNCONNECTED; > +} > + > static int vsock_connect(struct socket *sock, struct sockaddr_unsized *addr, > int addr_len, int flags) > { > @@ -1863,8 +2261,7 @@ static int vsock_connect(struct socket *sock, struct > sockaddr_unsized *addr, > * sk_state == TCP_SYN_SENT, which hereby we break. > * In such case VIRTIO_VSOCK_OP_RST will follow. > */ > - sk->sk_state = TCP_CLOSE; > - sock->state = SS_UNCONNECTED; > + vsock_connect_close(sock); > > /* Try to cancel VIRTIO_VSOCK_OP_REQUEST skb sent out by > * transport->connect(). > @@ -1878,10 +2275,8 @@ static int vsock_connect(struct socket *sock, struct > sockaddr_unsized *addr, > } > > err = sock_error(sk); > - if (err) { > - sk->sk_state = TCP_CLOSE; > - sock->state = SS_UNCONNECTED; > - } > + if (err) > + vsock_connect_close(sock); [Severity: Medium] What happens in vsock_connect() when a socket reaches TCP_ESTABLISHED while sleeping in schedule_timeout(), and is then swept by vsock_g2h_reset_unreachable() before vsock_connect() reacquires lock_sock(sk)? While vsock_connect() has released lock_sock(sk) in schedule_timeout(), virtio_transport_recv_connecting() can receive VIRTIO_VSOCK_OP_RESPONSE, transition sk->sk_state to TCP_ESTABLISHED, set sock->state to SS_CONNECTED, and insert vsk into vsock_connected_table. Once established, a concurrent vsock_connectible_sendmsg() on another thread can acquire credits via virtio_transport_get_credit() (incrementing vvs->bytes_unsent) and enqueue VIRTIO_VSOCK_OP_RW skbs onto send_pkt_queue. If VSOCK_CMD_DEV_NETNS_SET then runs vsock_g2h_reset_unreachable() before vsock_connect() reacquires lock_sock(sk), it sets sk->sk_state to TCP_CLOSE and sk->sk_err to ECONNRESET while leaving sock->state as SS_CONNECTED. When vsock_connect() wakes up, the once-established check: if (sk->sk_state == TCP_ESTABLISHED || sk->sk_state == TCP_CLOSING) { err = 0; goto out_wait; } does not match because sk->sk_state is TCP_CLOSE rather than TCP_CLOSING (unlike virtio_transport_do_close()) and sock->state == SS_CONNECTED is not checked. If signal_pending(current) || timeout == 0 holds, vsock_connect() proceeds to call vsock_transport_cancel_pkt(vsk) -> virtio_transport_purge_skbs(), which purges the post-connection VIRTIO_VSOCK_OP_RW skbs without calling virtio_transport_consume_skb_sent() to decrement vvs->bytes_unsent. Doesn't this leak vvs->bytes_unsent and cause vsock_linger() on close() to block until sk_lingertime expires, similar to the issue fixed by commit 002541ef650b ("vsock: Do not allow signal/timeout on established sockets")? And if no signal or timeout is pending, vsock_connect() exits the wait loop, consumes sk->sk_err via sock_error(sk), calls vsock_connect_close(sock), and returns -ECONNRESET while leaving sock->state as SS_CONNECTED with sk->sk_err cleared to 0. Should vsock_g2h_reset_unreachable() set sk->sk_state = TCP_CLOSING like virtio_transport_do_close(), or should vsock_connect() also check for sock->state == SS_CONNECTED after schedule_timeout()? -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=4
