Re: [PATCH v2] vsock/hv_sock: don't finish a connection on a socket being released
From: Stefano Garzarella <sgarzare@redhat.com>
Date: 2026-09-22 12:33:19
Also in:
linux-hyperv, lkml, virtualization
On Sat, Sep 19, 2026 at 02:31:27PM +0200, Bartłomiej Dmitruk wrote:
hvs_open_connection() only checks sk->sk_state (TCP_LISTEN for a
host-initiated connection, TCP_SYN_SENT for a guest-initiated one) before
proceeding. __vsock_release() sets sk->sk_shutdown = SHUTDOWN_MASK and, for
a listener, flushes the accept queue, while leaving sk_state unchanged. A
VMBUS channel offer that races close() therefore still passes the state
check and either enqueues a child onto the already-flushed accept queue
(conn_from_host) or completes a connection on a socket being torn down
(!conn_from_host); the socket and its VMBUS channel then leak.
The virtio transport guards the listener case in
virtio_transport_recv_listen(); hv_sock has no equivalent. Add a
sk_shutdown == SHUTDOWN_MASK check to the common path right after
lock_sock(), so both the host- and guest-initiated paths bail out.
hv_sock holds lock_sock(sk) across hvs_open_connection(), so the check is
race-free.
This was found by code inspection; I do not have Hyper-V hardware to test on.
Fixes: ae0078fcf0a5 ("hv_sock: implements Hyper-V transport for Virtual Sockets (AF_VSOCK)")
Signed-off-by: Bartłomiej Dmitruk <redacted>
---
v2: move the SHUTDOWN_MASK check to the common checks after lock_sock() so it
also covers the guest-initiated (!conn_from_host) path; add Fixes tag
(Stefano Garzarella).
v1: https://lore.kernel.org/netdev/20260917220156.56015-1-bartlomiej.dmitruk@isec.pl/ (local)About v1, I see sashiko reporting some pre-existing issues https://lore.kernel.org/netdev/179003264046.2160803.3176959842906352107@kernel.org/ (local) The critical one seems real, can you check? Maybe it should be fixed before this change. Stefano
quoted hunk ↗ jump to hunk
diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c --- a/net/vmw_vsock/hyperv_transport.c +++ b/net/vmw_vsock/hyperv_transport.c@@ -322,6 +322,15 @@(!conn_from_host && sk->sk_state != TCP_SYN_SENT)) goto out; + /* __vsock_release() may have already set sk_shutdown = SHUTDOWN_MASK + * (and, for a listener, flushed the accept queue) while leaving the + * socket in TCP_LISTEN/TCP_SYN_SENT. Proceeding would enqueue a child + * onto a released listener, or complete a connection on a released + * socket, leaking it and its VMBUS channel. + */ + if (sk->sk_shutdown == SHUTDOWN_MASK) + goto out; + if (conn_from_host) { if (sk_acceptq_is_full(sk)) goto out;