x86/crash: fix crash_setup_memmap_entries() out-of-bounds access

[Dave Young]

On 04/16/21 at 01:28pm, Mike Galbraith wrote:
> On Fri, 2021-04-16 at 19:07 +0800, Dave Young wrote:
> >
> > > We're excluding two ranges, allocate the scratch space we need to do that.
> >
> > I think 1 range should be fine, have you tested 1?
> 
> Have now, and vzalloc(struct_size(cmem, ranges, 1)) worked just fine.

Ok, thanks for your quick response.  Care to resend and cc x86 list and
Andrew?

Andrew usually takes core kexec/kdump fixes, x86 usually go through x86
maintainer.

Thanks
Dave