Subject: Re: stable-security kernel updates
To: Jiri Slaby <jslaby@suse.cz>, Greg KH <greg@kroah.com>
References: <5717DD8A.4000707@oracle.com> <571876AB.2060106@suse.cz>
 <5718B57D.4000504@oracle.com> <5718C0B8.8010609@suse.cz>
 <5718C215.7060703@suse.cz> <20160421123918.GA2294@kroah.com>
 <5718DB7F.2010701@oracle.com> <5718DFF3.8020306@suse.cz>
Cc: LKML <linux-kernel@vger.kernel.org>, stable <stable@vger.kernel.org>,
        lwn@lwn.net
From: Sasha Levin <sasha.levin@oracle.com>
Message-ID: <5718E362.5010402@oracle.com>
Date: Thu, 21 Apr 2016 10:27:46 -0400
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On 04/21/2016 10:13 AM, Jiri Slaby wrote:
> On 04/21/2016, 03:54 PM, Sasha Levin wrote:
>> On 04/21/2016 08:39 AM, Greg KH wrote:
>>> On Thu, Apr 21, 2016 at 02:05:41PM +0200, Jiri Slaby wrote:
>>>>> On 04/21/2016, 01:59 PM, Jiri Slaby wrote:
>>>>>>>>> (CVE-2016-2085) 613317b EVM: Use crypto_memneq() for digest comparisons
>>>>>>>
>>>>>>> Does not exist in the CVE database/is not confirmed yet AFAICS.
>>>>>
>>>>> And now I am looking at the patch and I remember why I threw it away.
>>>>> crypto_memneq is not in 3.12 yet and I was not keen enough to backport  it.
>>> Which brings up the question, Sasha, why did you think these CVEs were
>>> relevant for 3.12?  What were you basing that list on?
>>
>> The EVM one? Because there exists a vulnerability in the 3.12 EVM code which
>> allows an attacker to essentially circumvent integrity checks, and the reason
>> it wasn't fixed was because a memory comparison helper function wasn't backported?
> 
> Because sometimes the breakage risk is much higher than fixing a bug.
> This one was evaluated for 3.12.55 and not included at that time for
> that very reason.
> 
> Now, given it it upstream for much longer, I reevaluated that and put
> that into the 3.12 tree.

Okay, fair enough.

>> For the other CVEs I've listed? I looked at what went in to 3.14 but not 3.12,
>> and audited the resulting list to confirm that the vulnerability existed on 3.12.
> 
> Where exactly is 0185604 and 096fe9e contained in 3.14? I actually don't
> see them in any of Greg's stable tree.

You're right, I looked at the 3.18 tree rather than 3.14, where there are:

8dc1d26 KVM: x86: Reload pit counters for all channels when restoring state
3fee639 KEYS: Fix handling of stored error in a negatively instantiated user key

This means that missing CVE fixes are quite common with stable trees?


Thanks,
Sasha