Re: [Xen-devel] [PATCH 3/4] tools/libxc: Avoid generating inappropriate zero-length records

[Ian Jackson <ian.jackson@xxxxxxxxxxxxx>]

Wei Liu writes ("Re: [Xen-devel] [PATCH 3/4] tools/libxc: Avoid generating 
inappropriate zero-length records"):
> On Mon, Jul 25, 2016 at 06:15:37PM +0100, Ian Jackson wrote:
> > Is the ultimate bug that we are tripping over here simply that the
> > code calls malloc(0) and then bails if the libc produces NULL (as it
> > is entitled to do) ?
> 
> No, it isn't.
> 
> AIUI the issue is receiving end can't deal with zero-length record.  To
> to more precise, it is the hypervisor that chokes when toolstack issues
> an hypercall with the "malformed" data.

Oh.  So the hypervisor produces this zero-length data, but rejects it
when the same zero-length data is supplied back to it ?  That seems
like a bug in the hypervisor to me.

> If we go with David's approach, I think hypervisor should be made
> tolerant to zero-length record. That would be symmetric on both ends --
> hv can spit out as well as accept zero-length records. Toolstack should
> transparently send and receive records.

That would seem sensible to me.

Ian.

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