Re: [PATCH] Fix div by zero in xenvif if no queues.

["Durrant, Paul" <xadimgnik@xxxxxxxxx>]

On 21/03/2022 16:45, Martin Harvey wrote:
> -----Original Message-----
> From: win-pv-devel <win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx> On Behalf Of 
> Durrant, Paul
>
> > It really should not happen at all.
> I also notice, with some trepidation, that FrontendSetNumQueues does:
>
>      status = XENBUS_STORE(Read,
>                            &Frontend->StoreInterface,
>                            NULL,
>                            __FrontendGetBackendPath(Frontend),
>                            "multi-queue-max-queues",
>                            &Buffer);
>      if (NT_SUCCESS(status)) {
>          BackendMaxQueues = (ULONG)strtoul(Buffer, NULL, 10);
>
> So in the case where the contents of our xenstore buffer is not an integer, 
> we'll set backend max queues (and hence frontend max queues) to zero, without 
> so much of a whimper of an error, so that prob needs to be sorted too.
I really wouldn't go down that rathole. If the frontend cannot 
implicitly trust its backend (or the toolstack that creates it) then all 
bets are off IMO.
  Paul


> MH.