linux-kernel - Re: stable-security kernel updates

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Message-ID: <5718DD39.40808@oracle.com>
Date:	Thu, 21 Apr 2016 10:01:29 -0400
From:	Sasha Levin <sasha.levin@...cle.com>
To:	Greg KH <greg@...ah.com>
Cc:	Willy Tarreau <w@....eu>, Jiri Slaby <jslaby@...e.cz>,
	LKML <linux-kernel@...r.kernel.org>,
	stable <stable@...r.kernel.org>, lwn@....net
Subject: Re: stable-security kernel updates

On 04/21/2016 08:36 AM, Greg KH wrote:
> On Thu, Apr 21, 2016 at 07:27:39AM -0400, Sasha Levin wrote:
>> Hey Willy,
>>
>> On 04/21/2016 03:11 AM, Willy Tarreau wrote:
>>> This illustrates exactly what I suspected would happen because that's the
>>> same trouble we all face when picking backports for our respective trees
>>> except that since the selection barrier is much higher here, lots of
>>> important ones will be missing
>>
>> Right. I fully agree that there will be important security commits that'll
>> get missed, whether because they were missed in the stable selection or
>> the stable-security selection.
>>
>> I'd like to point out again that updating the entire stable tree is the
>> preferable way to patch against security (and non-security) issues.
> 
> s/preferable/only/ :)

Really? Even though as I showed updating your stable tree religiously would
still leave you vulnerable to "ancient" privesc exploits?

If anything, the *only* way is updating the entire kernel tree.

>> The
>> stable-security tree is a best-effort solution to provide a stop-gap in
>> between said stable tree updates.
> 
> What are you "stop-gapping" then?  The 7-10 days between stable
> releases?

In a perfect world where everyone has a team of kernel hackers on hand
reviewing stable commits, verifying the resulting kernel doesn't regress
their product, and fixes existing regressions for their product it might
be 7-10 days.

In the real world, this process takes much longer.

Doing a full rebase of the kernel tree is a much more costly process than
cherry picking a handful of security commits.

Thanks,
Sasha