[PATCH] proc/kcore: Don't bounds check against address 0

[Andrew Morton]

On Tue,  1 May 2018 13:11:43 -0700 Laura Abbott <labbott at redhat.com> wrote:

> The existing kcore code checks for bad addresses against
> __va(0) with the assumption that this is the lowest address
> on the system. This may not hold true on some systems (e.g.
> arm64) and produce overflows and crashes. Switch to using
> other functions to validate the address range.
> 
> Tested-by: Dave Anderson <anderson at redhat.com>
> Signed-off-by: Laura Abbott <labbott at redhat.com>
> ---
> I took your previous comments as a tested by, please let me know if that
> was wrong. This should probably just go through -mm. I don't think this
> is necessary for stable but I can request it later if necessary.

I'm surprised.  "overflows and crashes" sounds rather serious??