From: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx> Sent: Wednesday, April 20, 2022 1:07 PM
>
> For additional robustness in the face of Hyper-V errors or malicious
> behavior, validate all values that originate from packets that Hyper-V
> has sent to the guest in the host-to-guest ring buffer. Ensure that
> invalid values cannot cause data being copied out of the bounds of the
> source buffer in hvs_stream_dequeue().
>
> Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx>
> ---
> include/linux/hyperv.h | 5 +++++
> net/vmw_vsock/hyperv_transport.c | 11 +++++++++--
> 2 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> index fe2e0179ed51e..55478a6810b60 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -1663,6 +1663,11 @@ static inline u32 hv_pkt_datalen(const struct
> vmpacket_descriptor *desc)
> return (desc->len8 << 3) - (desc->offset8 << 3);
> }
>
> +/* Get packet length associated with descriptor */
> +static inline u32 hv_pkt_len(const struct vmpacket_descriptor *desc)
> +{
> + return desc->len8 << 3;
> +}
>
> struct vmpacket_descriptor *
> hv_pkt_iter_first_raw(struct vmbus_channel *channel);
> diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
> index 8c37d07017fc4..092cadc2c866d 100644
> --- a/net/vmw_vsock/hyperv_transport.c
> +++ b/net/vmw_vsock/hyperv_transport.c
> @@ -577,12 +577,19 @@ static bool hvs_dgram_allow(u32 cid, u32 port)
> static int hvs_update_recv_data(struct hvsock *hvs)
> {
> struct hvs_recv_buf *recv_buf;
> - u32 payload_len;
> + u32 pkt_len, payload_len;
> +
> + pkt_len = hv_pkt_len(hvs->recv_desc);
> +
> + /* Ensure the packet is big enough to read its header */
> + if (pkt_len < HVS_HEADER_LEN)
> + return -EIO;
>
> recv_buf = (struct hvs_recv_buf *)(hvs->recv_desc + 1);
> payload_len = recv_buf->hdr.data_size;
>
> - if (payload_len > HVS_MTU_SIZE)
> + /* Ensure the packet is big enough to read its payload */
> + if (payload_len > pkt_len - HVS_HEADER_LEN || payload_len > HVS_MTU_SIZE)
> return -EIO;
>
> if (payload_len == 0)
> --
> 2.25.1
Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
