Re: [Xen-devel] out of bounds handling for get_mfn_from_gpfn()

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 26 Apr 2006, at 15:28, Jan Beulich wrote:

> > Okay, maybe we need to be more restrictive: 20 bits for 32b (4GB), 22
> > bits for 32b-pae (16GB), and some suitable large value for 64b (31
> > would be fine, it's good for up to 8TB).
> Then perhaps the way to go would be to really check against
> ((RO_MPT_VIRT_END - RO_MPT_VIRT_START) / 
> sizeof(*phys_to_machine_mapping)).
> This wouldn't be 31 bits for x86-64, but it seems to me that allowing 
> 35-bit gpfn-s
> wouldn't be that bad an idea (and the fact that the array currently 
> may only get
> populated up to 31-bit gpfn-s wouldn't seem to cause any problems). 
> I'll prepare a
> patch...
Okay, that's a reasonable way to go. Please define a macro to hide the 
RO_MPT arithmetic though.
Maybe NR_PHYSMACHINE_TABLE_ENTRIES or something like that...

 -- Keir


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