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Date:   Thu, 21 Nov 2019 17:03:35 -0800
From:   Jakub Kicinski <jakub.kicinski@netronome.com>
To:     Haiyang Zhang <haiyangz@microsoft.com>
Cc:     "sashal@kernel.org" <sashal@kernel.org>,
        "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        KY Srinivasan <kys@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        "olaf@aepfle.de" <olaf@aepfle.de>, vkuznets <vkuznets@redhat.com>,
        "davem@davemloft.net" <davem@davemloft.net>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net,v2 1/2] hv_netvsc: Fix offset usage in
 netvsc_send_table()
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On Fri, 22 Nov 2019 00:54:20 +0000, Haiyang Zhang wrote:
> > >
> > > -	tab = (u32 *)((unsigned long)&nvmsg->msg.v5_msg.send_table +
> > > -		      nvmsg->msg.v5_msg.send_table.offset);
> > > +	if (offset > msglen - count * sizeof(u32)) {  
> > 
> > Can't this underflow now? What if msglen is small?  
> msglen came from the vmbus container message. We trust it to be big
> enough for the data region.

Ok, it looked like it was read from some descriptor which could
potentially be controlled by "the other side" but I trust your
judgement :)

Both patches LGTM, then.