Re: [PATCH tip/core/rcu 02/20] torture: Prepare scripting for shift from %p to %pK

[Linus Torvalds]

On Sun, Dec 10, 2017 at 4:52 AM, Andy Shevchenko
<andy.shevchenko@xxxxxxxxx> wrote:
>>
>>> Perhaps it should have printed a fixed, non-zero value for non-zero
>>> pointers.
>>
>> I must leave this to the people who have a dog in that contest.  ;-)
>
> Since there is an ongoing discussion with security people near to %pK
> and alike, I added Kees and Linus to Cc list.
>
> The proposed change can be done easily, though I have no knowledge
> about possible implications.

I'd rather make %pK act more like %p than have gratuitous differences.

I also think %pK is kind of pointless in general. It has not been a
big success, and the whole "root or not" is kind of nasty anyway. Root
in a container? Things like that.

So I think that if people worry  about leaking pointers, they should
primarily go for:

 - just use %p and now get the hashed value

 - if the hashed value is pointless, ask yourself whether the pointer
itself is important. Maybe it should be removed?

 - as a last option, if you really  think the true pointer value is
important, why is root so special, and maybe you should use %px and
make sure you have proper sensible permissions.

..and %pK just isn't really the answer in any of those cases.

         Linus