KASLR support on ARM with Kernel 4.9 and 4.14

[Pintu Agarwal]

On Tue, 29 Sep 2020 at 01:20, Kees Cook <keescook at chromium.org> wrote:

> Note that I still can't explain what you're seeing. /proc/kallsyms
> shouldn't be affected by these patches -- I would expect it to either
> report the true value or 00s.
>
> > I will disable kptr_restrict and check or, I will enable
> > CONFIG_DEBUG_CONSOLE_UNHASHED_POINTERS and check.
>
> I would start with kptr_restrict=0 and see if that changes the contents
> of /proc/kallsyms. If it does, then it is the hashing. If it doesn't,
> well, we're back to square one. :)

Actually in that board, the kptr_restrict=0 already in both case: 4.9
and 4.14 Kernel boards.
In another board with 4.14 and kptr_restrict=2, I see that the
addresses are 00 always.

I further checked that when I enable this config:
CONFIG_DEBUG_CONSOLE_UNHASHED_POINTERS,
then the addresses are remaining the same in every boot.
But this particular config is not present in 4.9 Kernel.
So, I think it is controlled using this config.

--
Pintu