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Date:   Thu, 21 Apr 2022 15:50:57 +0200
From:   Stefano Garzarella <sgarzare@redhat.com>
To:     "Andrea Parri (Microsoft)" <parri.andrea@gmail.com>
Cc:     KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
        Michael Kelley <mikelley@microsoft.com>,
        David Miller <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, linux-hyperv@vger.kernel.org,
        virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/5] hv_sock: Check hv_pkt_iter_first_raw()'s return value
Message-ID: <20220421135057.57whrntjdv25jqpl@sgarzare-redhat>
References: <20220420200720.434717-1-parri.andrea@gmail.com>
 <20220420200720.434717-2-parri.andrea@gmail.com>
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On Wed, Apr 20, 2022 at 10:07:16PM +0200, Andrea Parri (Microsoft) wrote:
>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@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: Stefano Garzarella <sgarzare@redhat.com>