Re: Creating a function for exposing memory usage of backend process

On Fri, Jul 31, 2020 at 03:23:52PM -0400, Robert Haas wrote:
> On Fri, Jul 31, 2020 at 4:25 AM torikoshia <torikoshia(at)oss(dot)nttdata(dot)com> wrote:
>> And as Fujii-san told me in person, exposing memory address seems
>> not preferable considering there are security techniques like
>> address space layout randomization.
>
> Yeah, exactly. ASLR wouldn't do anything to improve security if there
> were no other security bugs, but there are, and some of those bugs are
> harder to exploit if you don't know the precise memory addresses of
> certain data structures. Similarly, exposing the addresses of our
> internal data structures is harmless if we have no other security
> bugs, but if we do, it might make those bugs easier to exploit. I
> don't think this information is useful enough to justify taking that
> risk.

FWIW, this is the class of issues where it is possible to print some
areas of memory, or even manipulate the stack so as it was possible to
pass down a custom pointer, so exposing the pointer locations is a
real risk, and this has happened in the past. Anyway, it seems to me
that if this part is done, we could just make it superuser-only with
restrictive REVOKE privileges, but I am not sure that we have enough
user cases to justify this addition.
--
Michael