Re: [PATCH v3 0/6] implement KASLR for powerpc/fsl_booke/64
From: Linus Torvalds
Date: Thu Mar 05 2020 - 13:51:48 EST
On Wed, Mar 4, 2020 at 3:16 PM Scott Wood <oss@xxxxxxxxxxxx> wrote:
>
> The frustration is with the inability to set a flag to say, "I'm debugging and
> don't care about leaks... in fact I'd like as much information as possible to
> leak to me."
Well, I definitely don't want to tie it to "I turned off kaslr in
order to help debugging". That just means that now you're debugging a
kernel that is fundamentally different from what people are running.
So I'd much rather have people just set a really magic flag, perhaps
when kgdb is in use or something.
> In any case, this came up now due to a question about what to use when
> printing crash dumps. PowerPC currently prints stack and return addresses
> with %lx (in addition to %pS in the latter case) and someone proposed
> converting them to %p and/or removing them altogether.
Please just use '%pS'.
The symbol and offset is what is useful when users send crash-dumps.
The hex value is entirely pointless with kaslr - which should
basically be the default.
Note that this isn't about security at that point - crash dumps are
something that shouldn't happen, but if they do happen, we want the
pointers. But the random hex value just isn't _useful_, so it's just
making things less legible.
Linus