From ae6fcfbf5f03de3407b809aaee319330d3dc7f8b Mon Sep 17 00:00:00 2001 From: Stefano Garzarella Date: Thu, 17 Oct 2019 14:44:03 +0200 Subject: [PATCH] vsock/virtio: discard packets if credit is not respected If the remote peer doesn't respect the credit information (buf_alloc, fwd_cnt), sending more data than it can send, we should drop the packets to prevent a malicious peer from using all of our memory. This is patch follows the VIRTIO spec: "VIRTIO_VSOCK_OP_RW data packets MUST only be transmitted when the peer has sufficient free buffer space for the payload" Signed-off-by: Stefano Garzarella Signed-off-by: David S. Miller --- net/vmw_vsock/virtio_transport_common.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c index db127a69f5c3..481f7f8a1655 100644 --- a/net/vmw_vsock/virtio_transport_common.c +++ b/net/vmw_vsock/virtio_transport_common.c @@ -204,10 +204,14 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, return virtio_transport_get_ops()->send_pkt(pkt); } -static void virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs, +static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs, struct virtio_vsock_pkt *pkt) { + if (vvs->rx_bytes + pkt->len > vvs->buf_alloc) + return false; + vvs->rx_bytes += pkt->len; + return true; } static void virtio_transport_dec_rx_pkt(struct virtio_vsock_sock *vvs, @@ -879,14 +883,18 @@ virtio_transport_recv_enqueue(struct vsock_sock *vsk, struct virtio_vsock_pkt *pkt) { struct virtio_vsock_sock *vvs = vsk->trans; - bool free_pkt = false; + bool can_enqueue, free_pkt = false; pkt->len = le32_to_cpu(pkt->hdr.len); pkt->off = 0; spin_lock_bh(&vvs->rx_lock); - virtio_transport_inc_rx_pkt(vvs, pkt); + can_enqueue = virtio_transport_inc_rx_pkt(vvs, pkt); + if (!can_enqueue) { + free_pkt = true; + goto out; + } /* Try to copy small packets into the buffer of last packet queued, * to avoid wasting memory queueing the entire buffer with a small