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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Scott Wood <oss@buserror.net>
Cc: Kees Cook <keescook@chromium.org>,
	Jason Yan <yanaijie@huawei.com>, Petr Mladek <pmladek@suse.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	lkml <linux-kernel@vger.kernel.org>,
	"Tobin C . Harding" <tobin@kernel.org>,
	Daniel Axtens <dja@axtens.net>
Subject: Re: [PATCH v3 0/6] implement KASLR for powerpc/fsl_booke/64
Date: Thu, 5 Mar 2020 12:51:33 -0600	[thread overview]
Message-ID: <CAADWXX8guqt=Yz-Lo+qU6Ed0t-mG-B=UkqSDaSr3bH+Q2aOn-Q@mail.gmail.com> (raw)
In-Reply-To: <b5854fd867982527c107138d52a61010079d2321.camel@buserror.net>

On Wed, Mar 4, 2020 at 3:16 PM Scott Wood <oss@buserror.net> 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

  parent reply	other threads:[~2020-03-05 18:51 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-04 12:47 [PATCH] vfsprintf: only hash addresses in security environment Jason Yan
2020-03-04 15:12 ` Andy Shevchenko
2020-03-04 18:34 ` Kees Cook
2020-03-04 21:11   ` [PATCH v3 0/6] implement KASLR for powerpc/fsl_booke/64 Scott Wood
2020-03-04 22:36     ` Kees Cook
2020-03-05 18:51     ` Linus Torvalds [this message]
2020-03-06 18:33       ` Scott Wood
  -- strict thread matches above, loose matches on Subject: below --
2020-02-06  2:58 Jason Yan
2020-02-13  3:00 ` Jason Yan
2020-02-20  3:33   ` Jason Yan
2020-02-26  7:16 ` Daniel Axtens
2020-02-26  8:18   ` Jason Yan
2020-02-26 11:41     ` Daniel Axtens
2020-02-27  1:55       ` Jason Yan
2020-02-28  5:53     ` Scott Wood
2020-02-28  6:47       ` Jason Yan
2020-02-29  4:28         ` Scott Wood
2020-02-29  7:27           ` Jason Yan
2020-02-29 22:54             ` Scott Wood
2020-03-02  2:17               ` Jason Yan
2020-03-02  3:24                 ` Scott Wood
2020-03-02  7:12                   ` Jason Yan
2020-03-02  8:47                     ` Scott Wood
2020-03-02  9:37                       ` Jason Yan
2020-03-04 21:21   ` Scott Wood
2020-03-05  3:22     ` Jason Yan

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