[coreboot] Rowhammer mitigation: RH activation probability

Carl-Daniel Hailfinger c-d.hailfinger.devel.2006 at gmx.net
Sun Dec 16 01:02:28 CET 2018

Actually, the latest Rowhammer attack is harder to exploit on laptops
due to the power saving features for row activation. Servers use a
different row activation strategy which has better performance, but also
enables one-location hammering.
See Gruss, Lipp, Schwarz, Genkin et al.:
Another Flip in the Wall of Rowhammer Defenses
2018 IEEE Symposium on Security and Privacy


On 14.12.2018 23:36, Taiidan at gmx.com wrote:
> Upon doing more research I am noting in regards to my previous post
> about vendors who claimed to solve the problem by doubling the RAM
> refresh rate in their firmware that according to [1] it only postpones
> the problem rather than eliminating it.
> [1]
> https://googleprojectzero.blogspot.de/2015/03/exploiting-dram-rowhammer-bug-to-gain.html
> On 12/14/2018 03:20 AM, Nico Huber wrote:> On 07.12.18 22:46,
> Taiidan at gmx.com wrote:
>>> rowhammer is almost entirely a laptop problem or for that matter
>>> anything that uses SODIMM's due to their high density.
>> That doesn't seem right. Can you give any examples of chips commonly
>> used on SO-DIMMs that can't be found on DIMMs?
> Ahhh good point commodity parts.
>> I had the feeling you find the same chips on both. SO-DIMMs often host
> 16 chips. If you'd
>> want the same capacity on a DIMM with less chip density, you'd need
>> 32 chips (or physically bigger chips). Never seen that (though didn't
>> look for it either).
> I had read it somewhere awhile back when the problem first appeared
> stating that it didn't appear as much in desktops and servers due to
> lower density RAM which made sense to me considering the size difference
> I also tested my various home computers and only my laptops had a
> problem not the desktops/servers (all have ecc but it didn't show any
> errors) so I figured that it was an accurate statement. This shows the
> value of going back to quickly research something before providing the
> statement (and having others who aren't me to review!)
> On 12/14/2018 12:21 PM, ron minnich wrote:
>> So, at first we have a non-specific ad-hominem attack:
> I want people to get the best advice possible (hence my list of
> alternative sources) and while I can cite examples I am prohibited from
> potentially starting arguments about them so I do not want to.
> To me providing good advice is important since someone reading it could
> be facing a life or death situation such as a journalist in a hostile
> country and why I always apologize and note a correction if I give wrong
> advice. I am also a better sysadmin than I am a programmer so I
> concentrate on my strong points.
>> On Fri, Dec 7, 2018 at 1:53 PM Taiidan at gmx.com <Taiidan at gmx.com> wrote:
>>> I would like to note that company has provided poor security advice on a
>>> variety of occasions
>> followed by poor security advice:
>>> rowhammer is almost entirely a laptop problem or for that matter
>>> anything that uses SODIMM's due to their high density.
>> which is immediately disproven with a 3 term search on google:
>> https://cloud.google.com/blog/products/gcp/7-ways-we-harden-our-kvm-hypervisor-at-google-cloud-security-in-plaintext
>> "The Google Project Zero team led the way in discovering practical
>> Rowhammer attacks against client platforms. Google production machines
>> use double refresh rate to reduce errors, and ECC RAM that detects and
>> corrects Rowhammer-induced errors."
>> so, please all, no ad-hominem attacks, and if you're going to make a
>> technical claim, please be ready to provide justification.
> I had read it in a whitepaper somewhere and I am attempting to find out
> where.
> That is a good idea to have a citation on hand for claims like this and
> I will do so from now on as if I were editing the wiki.
>> thanks
>> ron
> If a post of mine is not acceptable then I encourage you or others to
> exorcise your right to deny it as sometimes I do not realize what is and
> what isn't considered okay.

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