Re: [PATCH] [Backport for stable 5.11] arm64: mm: correct the inside linear map boundaries during hotplug check

[Sasha Levin]

On Mon, Mar 29, 2021 at 10:28:47AM -0400, Pavel Tatashin wrote:
> commit ee7febce051945be28ad86d16a15886f878204de upstream.
>
> Memory hotplug may fail on systems with CONFIG_RANDOMIZE_BASE because the
> linear map range is not checked correctly.
>
> The start physical address that linear map covers can be actually at the
> end of the range because of randomization. Check that and if so reduce it
> to 0.
>
> This can be verified on QEMU with setting kaslr-seed to ~0ul:
>
> memstart_offset_seed = 0xffff
> START: __pa(_PAGE_OFFSET(vabits_actual)) = ffff9000c0000000
> END:   __pa(PAGE_END - 1) =  1000bfffffff
>
> Fixes: 58284a901b42 ("arm64/mm: Validate hotplug range before creating linear mapping")
> Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
> Tested-by: Tyler Hicks <tyhicks@xxxxxxxxxxxxxxxxxxx>
> Reviewed-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>

Queued up, thanks!

--
Thanks,
Sasha