linux-kernel - Re: [PATCH 0/2] introduce DUMP_PREFIX

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Message-ID: <CAHk-=wjnEV2E6vCRxv5S5m27iOjHeVWNbfK=JV8qxot4Do-FgA@mail.gmail.com>
Date:   Wed, 20 Jan 2021 11:39:49 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Timur Tabi <timur@...nel.org>, Kees Cook <keescook@...omium.org>,
        Matthew Wilcox <willy@...radead.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        roman.fietze@...na.com, Steven Rostedt <rostedt@...dmis.org>,
        John Ogness <john.ogness@...utronix.de>,
        Linux-MM <linux-mm@...ck.org>,
        Akinobu Mita <akinobu.mita@...il.com>
Subject: Re: [PATCH 0/2] introduce DUMP_PREFIX_UNHASHED for hex dumps

On Wed, Jan 20, 2021 at 1:19 AM Petr Mladek <pmladek@...e.com> wrote:
>
> And we should definitely add Linus into CC when sending v2.
> His expected opinion has been mentioned several times in this
> thread. It would be better to avoid these speculations
> and get his real opinion. IMHO, it is too late to add
> him in this long thread.

I've seen it, I've just not cared deeply.

I suspect the main issue is if you can cause debug dumps as a normal
user and find kernel addresses that way, but I'm not sure how much we
care. Somebody _actively_ debugging things might need the address, and
KASRL etc be damned.

I also suspect that everybody has already accepted that KASLR isn't
really working locally anyway (due to all the hw leak models with
cache and TLB timing), so anybody who can look at kernel messages
already probably could figure most of those things out.

So as long as the dumping isn't doing something actively stupid, and
as long as hex dumping isn't something that is easily triggered, this
probably falls under "nobody cares".

             Linus