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Date: Fri, 4 Aug 2017 19:36:58 +0200
From: Solar Designer <solar@...nwall.com>
To: Andrey Konovalov <andreyknvl@...il.com>
Cc: oss-security@...ts.openwall.com, willemdebruijn.kernel@...il.com,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Kostya Serebryany <kcc@...gle.com>
Subject: Re: Reporting and disclosing Linux kernel vulnerabilities

On Fri, Aug 04, 2017 at 06:59:15PM +0200, Andrey Konovalov wrote:
> It's not completely clear to me how to properly report and disclose
> Linux kernel security issues. There are a few different parties [1, 2,
> 3] that need to be informed and coordinated. I couldn't find a
> publicly available actionable list of steps, so I've outlined it as I
> see it here:
> 
> https://github.com/google/syzkaller/blob/master/docs/linux_kernel_reporting_bugs.md#reporting-security-bugs

Thank you!  I'm afraid the reality is that preferences vary, including
even between different upstream developers.  That said, we should in
fact probably try to come up with guidelines similar to what you made a
start at.

Here are some assorted comments from me:

Please inform oss-security as soon as the issue is made public,
anywhere.  There's no need to wait for a CVE, patch, nor anything to do
that.  If the issue is public, it must be on oss-security right away.
You should add CVE, patch, etc. by "replying" to your own message later.
This especially makes a difference in your "Reporting minor security
bugs", where making the issue public is currently listed as step 1, and
posting it to oss-security as step 3, with a potentially time-consuming
step 2 inbetween (waiting for a CVE).  Both must be part of step 1, or
for clarity they may be steps 1 and 2 if there's expected to be no delay
between them.

In "Reporting major security bugs", you could make it clearer that
there's no or little delay between notification to security@... and to
linux-distros.  As currently written, it is unclear whether you
recommend to wait for security@... to come up with a patch before
informing linux-distros.

I hear that for netdev bugs, security@... is likely to ask you to post
such bugs to the public netdev list right away, without any embargo.
You could want to see whether this is in fact the case, and adjust your
instructions if so.

I don't know whether the CNAs on linux-distros have control to "make the
CVE description public" as you suggest as one of the steps.  This is a
question to them - can they?  I assume this means the description isn't
available to MITRE nor anyone outside of linux-distros (and the distros'
people with need-to-know) before that step.

Just like in "Reporting minor security bugs", there should be almost no
delays between the different public disclosure steps - CVE description,
distros' updates, upstream commit, notification to oss-security.  All of
these should be on the same day, at worst.  Perhaps clarify this.

When you refer to linux-distros, please ask people to carefully read the
distros list wiki page before sending anything to the list.  They must
be aware of list policy, and they must learn of the magic string to
include in the Subject from there (do not list this magic string in your
own instructions, though - just like you correctly don't do it now).

The "good example" of oss-security posting that you refer to does in
fact demonstrate a good oss-security posting, but it also demonstrates
problematic handling of the issue before that point.  Here's the
timeline found in that message:

2016-11-28: Bug reported to security () kernel org
2016-11-30: Patch submitted to netdev, notification sent to linux-distros
2016-12-02: Patch committed to mainline kernel
2016-12-06: Public announcement

"2016-11-30: Patch submitted to netdev" essentially means making the
issue public.  (I guess this is an instance of what I had meant above
regarding netdev issues being forced to the public from security@....)
After that time, there was no point in "notification sent to
linux-distros" (which is for private issues only), and instead
"2016-12-06: Public announcement" should have occurred on oss-security
right away on 2016-11-30 (all linux-distros members are supposed to
monitor oss-security).  Keeping the issue "semi-"public like that is
generally wrong.

(I don't recall the details of why we let it happen the way it did for
that one issue last year.  My comments above are in general.)

That's it for now.  I'm sorry for not having a set of clear and simple
edits to your current proposal, but I do hope this thread will result in
a better "publicly available actionable list of steps", as you suggest.
Thank you for working on it!

> [1] https://www.kernel.org/doc/html/latest/admin-guide/security-bugs.html
> 
> [2] http://oss-security.openwall.org/wiki/mailing-lists/distros
> 
> [3] http://oss-security.openwall.org/wiki/mailing-lists/oss-security

Alexander

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