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From: Steven Rostedt <rostedt@goodmis.org>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: Jann Horn <jannh@google.com>,
	Golden_Miller83@protonmail.ch, greg@kroah.com,
	Kees Cook <keescook@google.com>,
	salyzyn@android.com, LKML <linux-kernel@vger.kernel.org>,
	mingo@redhat.com, kernel-team@android.com,
	stable@vger.kernel.org, kernel-hardening@lists.openwall.com
Subject: Re: [PATCH] tracing: do not leak kernel addresses
Date: Fri, 27 Jul 2018 14:31:41 -0400	[thread overview]
Message-ID: <20180727143141.4b53d554@gandalf.local.home> (raw)
In-Reply-To: <CAKwvOdmg4DSSwy9YBccYWzc+6ZU2yKSSFmfnj72wqbYDJU0gzw@mail.gmail.com>

On Fri, 27 Jul 2018 11:13:51 -0700
Nick Desaulniers <ndesaulniers@google.com> wrote:

> I found the internal bug report (reported Jan '17, you'll have to
> forgive me if my memory of the issue is hazy, or if the fix used at
> the time wasn't perfect), which was reported against the Nexus 6.
> >From the report, it was possible to `cat  
> /sys/kernel/debug/tracing/printk_formats` without being root, which I
> can't do on my workstations much more modern kernel (Nexus 6 was
> 3.10).  So I guess the question is what governs access to files below
> /sys/kernel/debug, and why was it missing from those kernels?  I
> assume some check was added, but either not backported to 3.10 stable
> (or more likely not pulled in to Nexus 6's kernel through stable;
> Android is now in a much better place for that kind of issue).

As of commit 82aceae4f0d4 ("debugfs: more tightly restrict default
mount mode") /sys/kernel/debug has been default mounted as 0700 (root
only). But that was introduced in 3.7. Not sure why your 3.10 kernel
didn't have that. Perhaps there's another commit that fixed
permissions not being inherited?

-- Steve

  reply	other threads:[~2018-07-27 18:31 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-25 20:22 [PATCH] tracing: do not leak kernel addresses Mark Salyzyn
2018-07-25 21:14 ` Nick Desaulniers
2018-07-26  1:07 ` Steven Rostedt
2018-07-26 15:14   ` Mark Salyzyn
2018-07-26 15:22     ` Steven Rostedt
2018-07-26 16:32       ` Nick Desaulniers
2018-07-26 16:37         ` Steven Rostedt
2018-07-26 16:59           ` Nick Desaulniers
2018-07-26 21:56             ` Nick Desaulniers
2018-07-26 15:31     ` Greg KH
2018-07-26 16:52       ` Nick Desaulniers
2018-07-26 22:15         ` Steven Rostedt
2018-07-27 12:07           ` Jordan Glover
2018-07-27 13:40             ` Jann Horn
2018-07-27 13:47               ` Steven Rostedt
2018-07-27 18:13                 ` Nick Desaulniers
2018-07-27 18:31                   ` Steven Rostedt [this message]
     [not found]                     ` <CAMx4XWv3OazvURuN1XU2+5C5tNDzPuTniMn_T=XTA4P8_uwS_A@mail.gmail.com>
2018-07-27 18:47                       ` Jann Horn
2018-07-27 18:58                         ` Jann Horn
2018-07-27 19:54                           ` Theodore Y. Ts'o
2018-07-27 20:11                             ` Steven Rostedt
2018-07-27 20:21                               ` Theodore Y. Ts'o
2018-07-27 20:53                                 ` Steven Rostedt
2018-07-27 22:05                                 ` Sandeep Patil
2018-07-28  0:04                                   ` Theodore Y. Ts'o
2018-07-30 14:35                                     ` Sandeep Patil

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