Virtualization - Apr 2022 - [PATCH 1/5] hv_sock: Check hv_pkt_iter_first_raw()'s return value

From: Andrea Parri (Microsoft) <parri.andrea at gmail.com> Sent:
Wednesday, April 20, 2022 1:07 PM
> 
> The function returns NULL if the ring buffer doesn't contain enough
> readable bytes to constitute a packet descriptor.  The ring buffer's
> write_index is in memory which is shared with the Hyper-V host, an
> erroneous or malicious host could thus change its value and overturn
> the result of hvs_stream_has_data().
> 
> Signed-off-by: Andrea Parri (Microsoft) <parri.andrea at gmail.com>
> ---
>  net/vmw_vsock/hyperv_transport.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/net/vmw_vsock/hyperv_transport.c
b/net/vmw_vsock/hyperv_transport.c
> index e111e13b66604..943352530936e 100644
> --- a/net/vmw_vsock/hyperv_transport.c
> +++ b/net/vmw_vsock/hyperv_transport.c
> @@ -603,6 +603,8 @@ static ssize_t hvs_stream_dequeue(struct vsock_sock
*vsk,
> struct msghdr *msg,
> 
>  	if (need_refill) {
>  		hvs->recv_desc = hv_pkt_iter_first_raw(hvs->chan);
> +		if (!hvs->recv_desc)
> +			return -ENOBUFS;
>  		ret = hvs_update_recv_data(hvs);
>  		if (ret)
>  			return ret;
> --
> 2.25.1
Reviewed-by: Michael Kelley <mikelley at microsoft.com>