# \[PATCH net v3 2/2\] vsock/vmci: validate packet source for connected sockets - From: Daehyeon Ko \ - Date: 2026-08-23 17:59:48 - List: netdev - Page: https://ratatoskr.run/netdev/2026/08/17450347 - Thread: https://ratatoskr.run/netdev/2026/08/17450345/t.md ```text vmci_transport_recv_stream_cb() looks up sockets first by the full source and destination tuple, then by destination only in the bound table. The fallback can select a non-listening socket without checking whether the packet came from its stored peer. This was reproduced with two VMCI contexts. A RST from the context not stored in a TCP_SYN_SENT socket reset that socket after it was selected by the destination-only lookup. VMCI can process notification packets in bottom-half context when the socket is not owned by user context, or defer packets to a workqueue. Use vsock_check_source() after taking the socket lock in the bottom-half path, and recheck after lock_sock() in the workqueue path. Listening sockets continue to accept packets from any source. Fixes: d021c344051a ("VSOCK: Introduce VM Sockets") Reported-by: Sashiko Closes: https://lore.kernel.org/netdev/20260814121255.6B5001F000E9@smtp.kernel.org/ Cc: Suggested-by: Stefano Garzarella Assisted-by: Codex:gpt-5.6-sol Signed-off-by: Daehyeon Ko --- net/vmw_vsock/vmci_transport.c | 29 +++++++++++++++++++++++------ 1 file changed, 23 insertions(+), 6 deletions(-) diff --git a/net/vmw_vsock/vmci_transport.c b/net/vmw_vsock/vmci_transport.c index 1c4ee039c..b612a9893 100644 --- a/net/vmw_vsock/vmci_transport.c +++ b/net/vmw_vsock/vmci_transport.c @@ -680,11 +680,13 @@ static int vmci_transport_recv_stream_cb(void *data, struct vmci_datagram *dg) struct vmci_transport_packet *pkt; struct vsock_sock *vsk; bool bh_process_pkt; + bool drop_pkt; int err; sk = NULL; err = VMCI_SUCCESS; bh_process_pkt = false; + drop_pkt = false; /* Ignore incoming packets from resources that aren't vsock * implementations. @@ -765,17 +767,26 @@ static int vmci_transport_recv_stream_cb(void *data, struct vmci_datagram *dg) bh_lock_sock(sk); if (!sock_owned_by_user(sk)) { - /* The local context ID may be out of date, update it. */ - vsk->local_addr.svm_cid = dst.svm_cid; + if (sk->sk_state != TCP_LISTEN && + !vsock_check_source(vsk, &vmci_transport, &src)) { + drop_pkt = true; + err = VMCI_ERROR_NO_ACCESS; + } else { + /* The local context ID may be out of date, update it. */ + vsk->local_addr.svm_cid = dst.svm_cid; - if (sk->sk_state == TCP_ESTABLISHED) - vmci_trans(vsk)->notify_ops->handle_notify_pkt( - sk, pkt, true, &dst, &src, - &bh_process_pkt); + if (sk->sk_state == TCP_ESTABLISHED) + vmci_trans(vsk)->notify_ops->handle_notify_pkt(sk, pkt, true, + &dst, &src, + &bh_process_pkt); + } } bh_unlock_sock(sk); + if (drop_pkt) + goto out; + if (!bh_process_pkt) { struct vmci_transport_recv_pkt_info *recv_pkt_info; @@ -900,6 +911,7 @@ static void vmci_transport_recv_pkt_work(struct work_struct *work) { struct vmci_transport_recv_pkt_info *recv_pkt_info; struct vmci_transport_packet *pkt; + struct sockaddr_vm src; struct sock *sk; recv_pkt_info = @@ -908,6 +920,10 @@ static void vmci_transport_recv_pkt_work(struct work_struct *work) pkt = &recv_pkt_info->pkt; lock_sock(sk); + vsock_addr_init(&src, pkt->dg.src.context, pkt->src_port); + if (sk->sk_state != TCP_LISTEN && + !vsock_check_source(vsock_sk(sk), &vmci_transport, &src)) + goto out; /* The local context ID may be out of date. */ vsock_sk(sk)->local_addr.svm_cid = pkt->dg.dst.context; @@ -937,6 +953,7 @@ static void vmci_transport_recv_pkt_work(struct work_struct *work) break; } +out: release_sock(sk); kfree(recv_pkt_info); /* Release reference obtained in the stream callback when we fetched -- 2.54.0 ```