Subject: Re: [PATCH] uts: Don't randomize "struct uts_namespace".
To: Linus Torvalds <torva...@linux-foundation.org>, Ken'ichi Ohmichi
<oomi...@mxs.nes.nec.co.jp>, Masaki Tachibana <mas-tachib...@vf.jp.nec.com>,
Kazuhito Hagio <k-ha...@ab.jp.nec.com>
Cc: Kees Cook <keesc...@chromium.org>, Linux Kernel Mailing List
From: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp>
Date: Sat, 7 Jul 2018 08:10:08 +0900
I noticed that makedumpfile ( https://sourceforge.net/p/makedumpfile/code/ )
can no longer detect kernel version correctly because "struct uts_namespace"
(which is exposed to userspace via vmcoreinfo) is subjected to randomization
by GCC_PLUGIN_RANDSTRUCT kernel config option since 4.13.
The code was introduced by below commit.
Author: ken1_ohmichi <ken1_ohmichi>
Date: Fri Dec 22 07:41:14 2006 +0000
On linux-2.6.18 or former, the release information could be gotten from
the symbol "system_utsname". But on linux-2.6.19, it can be done from the
symbol "init_uts_ns". A new makedumpfile can get the release information
from the existing symbol.
Can you detect kernel version without using "struct uts_namespace" ?
On 2018/07/07 1:11, Linus Torvalds wrote:
> On Fri, Jul 6, 2018 at 3:07 AM Tetsuo Handa
> <penguin-ker...@i-love.sakura.ne.jp> wrote:
>> I noticed that makedumpfile utility is failing to check kernel version, for
>> it depends on offset of "struct uts_namespace"->name being sizeof(int).
> For something like this, we fix makedumpfile instead. This is not a
> "user program" using system calls etc, this is something that delves
> into the kernel dump and tries to make sense of it.
> Where is the makedumpfile source code? What is it trying to do, and why?
> One option is to just say "hey, you can't make much sense of a
> randomized kernel dump anyway, so don't even try".
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