netdev - Re: [PATCH 3/5] hv_sock: Add validation for untrusted Hyper-V values

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Date:   Thu, 21 Apr 2022 17:30:37 +0200
From:   Andrea Parri <parri.andrea@...il.com>
To:     Stefano Garzarella <sgarzare@...hat.com>
Cc:     KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, linux-hyperv@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5] hv_sock: Add validation for untrusted Hyper-V values

> > @@ -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)
> 
> checkpatch warns that we exceed 80 characters, I do not have a strong
> opinion on this, but if you have to resend better break the condition into 2
> lines.

Will break if preferred.  (but does it really warn??  I understand that
the warning was deprecated and the "limit" increased to 100 chars...)


> Maybe even update or remove the comment? (it only describes the first
> condition, but the conditions are pretty clear, so I don't think it adds
> much).

Works for me.  (taking it as this applies to the previous comment too.)

Thanks,
  Andrea