Thank you for your contribution! Sashiko AI review found 3 potential
issue(s) to consider.
Critical: 0 · High: 0 · Medium: 1 · Low: 2
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- [Medium] The invariant this patch asserts ("On a failed connect(),
transport is de-assigned", enforced by the new…
- [Low] Two in-tree comments still justify the SOCK_DEAD gating in
vsock_remove_sock() by the "transport reassignment" case, which…
- [Low] vsock_assign_transport() gains a hard precondition (the socket
must have neither ->transport nor ->trans set, otherwise WARN +…
--
vsock: drop the re-assignment logic
This removes the transport re-assignment path from vsock_assign_transport()
and replaces it with an assertion that the socket has no transport and no
private transport state yet. The rationale given is that a failed
connect() de-assigns the transport and a connected socket keeps its
transport until close().
> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> index 20181ddde114f..5cecd1c9c6e50 100644
> --- a/net/vmw_vsock/af_vsock.c
> +++ b/net/vmw_vsock/af_vsock.c
> @@ -604,6 +604,9 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct
> vsock_sock *psk)
> __u8 remote_flags;
> int ret;
>
> + if (WARN_ON_ONCE(vsk->transport || vsk->trans))
> + return -EINVAL;
> +
[Severity: Medium]
Is the invariant behind this assertion always true? The commit message
says "On a failed connect(), transport is de-assigned", but
vsock_unconnected_reset() can return early without de-assigning:
net/vmw_vsock/af_vsock.c:vsock_unconnected_reset() {
if (WARN_ON_ONCE(vsk->peer_shutdown) ||
WARN_ON_ONCE(sock_flag(sk, SOCK_DONE)) ||
WARN_ON_ONCE(sk->sk_state != TCP_SYN_SENT &&
sk->sk_state != TCP_CLOSE))
return;
...
vsock_deassign_transport(vsk);
...
}
With the VMCI transport, can a peer detach during the handshake produce
exactly that state? vmci_transport_recv_connecting_client_negotiate()
subscribes the detach callback while sk_state is still TCP_SYN_SENT, and
then:
net/vmw_vsock/vmci_transport.c:vmci_transport_handle_detach() {
sock_set_flag(sk, SOCK_DONE);
/* On a detach the peer will not be sending or receiving
* anymore.
*/
WRITE_ONCE(vsk->peer_shutdown, SHUTDOWN_MASK);
...
if (sk->sk_state == TCP_SYN_SENT) {
...
sk->sk_state = TCP_CLOSE;
sk->sk_err = ECONNRESET;
}
The blocking connect() then wakes on sk_err and takes:
net/vmw_vsock/af_vsock.c:vsock_connect() {
out_reset:
if (err)
vsock_unconnected_reset(sk);
}
so WARN_ON_ONCE(vsk->peer_shutdown) fires and the transport is never
de-assigned, leaving sock->state at SS_CONNECTING until close(). A later
vsock_assign_transport() on that socket would then hit the new assertion
added here.
At this commit there also seems to be a second, transport-independent way
in: a peer RESPONSE followed by RST leaves the socket in TCP_CLOSING with
SOCK_DONE and peer_shutdown set while connect() sleeps, and since the wait
loop here only breaks on TCP_ESTABLISHED, a signal or the connect timeout
routes to out_reset with err != 0 and trips the same warnings. That second
path looks like it is addressed later in the series by "vsock: treat
TCP_CLOSING as once-established" and the SS_CONNECTED guard from "vsock:
handle socket bricking due to transport event", but the VMCI detach case
appears to survive to the end of the series.
Would it make sense to make vsock_unconnected_reset() de-assign the
transport unconditionally, or to normalize SOCK_DONE/peer_shutdown there
before the checks?
[Severity: Low]
Could the new precondition be documented? vsock_assign_transport() is
EXPORT_SYMBOL_GPL'd and called by the transports
(virtio_transport_common.c, vmci_transport.c, hyperv_transport.c), but the
descriptive block above the function still only covers transport selection
and the -ENODEV case:
/* Assign a transport to a socket and call the .init transport callback.
*
* Note: for connection oriented socket this must be called when
vsk->remote_addr
* is set ...
* - anything else goes to h2g or returns -ENODEV if no h2g is available
*/
and the declaration in include/net/af_vsock.h carries no documentation. A
note that the function is one-shot per socket and now returns -EINVAL if
vsk->transport or vsk->trans is already set would help future callers.
[ ... ]
> @@ -668,26 +666,6 @@ int vsock_assign_transport(struct vsock_sock *vsk,
> struct vsock_sock *psk)
> */
> mutex_unlock(&vsock_register_mutex);
>
> - if (vsk->transport) {
> - /* transport->release() must be called with sock lock acquired.
> - * This path can only be taken during vsock_connect(), where we
> - * have already held the sock lock. In the other cases, this
> - * function is called on a new socket which is not assigned to
> - * any transport.
> - */
> - vsk->transport->release(vsk);
> - vsock_deassign_transport(vsk);
> -
> - /* transport's release() and destruct() can touch some socket
> - * state, since we are reassigning the socket to a new transport
> - * during vsock_connect(), let's reset these fields to have a
> - * clean state.
> - */
> - sock_reset_flag(sk, SOCK_DONE);
> - sk->sk_state = TCP_CLOSE;
> - WRITE_ONCE(vsk->peer_shutdown, 0);
> - }
> -
[Severity: Low]
With this block gone, two comments elsewhere in the file still explain a
load-bearing check in terms of reassignment. Should they be updated?
net/vmw_vsock/af_vsock.c:vsock_remove_sock() {
/* Transport reassignment must not remove the binding. */
if (sock_flag(sk_vsock(vsk), SOCK_DEAD))
vsock_remove_bound(vsk);
}
net/vmw_vsock/af_vsock.c:__vsock_release() {
/* Indicate to vsock_remove_sock() that the socket is being released and
* can be removed from the bound_table. Unlike transport reassignment
* case, where the socket must remain bound despite vsock_remove_sock()
* being called from the transport release() callback.
*/
sock_set_flag(sk, SOCK_DEAD);
}
The SOCK_DEAD test itself still looks necessary, but for other callers:
virtio_transport_recv_connected() and virtio_transport_remove_sock() on the
RST path, and hvs_do_close_lock_held() from hvs_close_connection(), all run
on live sockets without SOCK_DEAD set. The reassignment reason the
comments name no longer exists after this patch.
--
Sashiko AI review ·
https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260922-vsock-connect-reset-closing-v3-0-78907b8200d4%40rbox.co
