Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Meltdown, aka “Dear Intel, you suck”

marc.info

Post reply on HN
Print view View original

71–80 of 176 posts

Re: Meltdown, aka “Dear Intel, you suck”

#71

Post by mannykannot »

discoursism wrote: post #51
Tomte wrote: post #47

Earlier quoted context omitted.

Don‘t they refuse to honor embargoes? That would be an explanation why they got no information privately.

Here's an LWN article that references Theo's position on embargoes: https://lwn.net/Articles/601958/

This article seems to suggest that of all the BSDs, only OpenBSD / Theo takes this position - at least in in the case of the OpenSSL problems, the others got advance notice and participated in the embargo.

It might be argued that the risk of the exploit making it into the wild would have been higher if the BSDs were notified, on account of the sort of accidental premature disclosure that actually happened. This would appear to be self-serving if stated by the embargo insiders, but it may still be valid, especially if my guesses that a) this problem's biggest potential impact is in cloud computing, and b) there is relatively little use of BSDs in cloud computing, are accurate.

Re: Meltdown, aka “Dear Intel, you suck”

#72

Post by tomxor »

madez wrote: post #52
DougN7 wrote: post #40

I don’t understand the Intel hate. It’s not like their engineers are dumb or lazy. This exploit is very hard to imagine before now. And it’s there because chip makers were trying to wring out more performance. It’s unfortunate if anythig.

Well, there is the ME for one, an omnipotent, mandatory backdoor. Then there are _many_ undocumented opcodes. What does 0f0d00 do? What 0f78c0? What dbe0? I can continue for a very long time. These are just some known unknowns. If you still need more reasons, they are uncooperative when it comes to certain other firmware blobs. If you are open to arguments, there are many good reasons to take a negative stance toward…

To be fair gmail flags basically any code, if it's zipped i've found it only needs to vaguely resemble code. basically gmail is only safe for sending image formats and document formats that it knows of and don't contain macros, then it's just a crapshoot that you don't get matched a false positive. Gmail is far from developer friendly anymore.

Re: Meltdown, aka “Dear Intel, you suck”

#73

Post by forgotpw2018 »

DougN7 wrote: post #40

I don’t understand the Intel hate. It’s not like their engineers are dumb or lazy. This exploit is very hard to imagine before now. And it’s there because chip makers were trying to wring out more performance. It’s unfortunate if anythig.

All other chipmakers are 'immune' to Meltdown precisely because the attack is obvious. Cache timing is hard, but speculating execution before checking permissions is plain dumb.

If it was such a mythical attack why doesn't it work on anyone else's chips? Intel screwed up hard on this and I have no sympathy. Hopefully the incoming lawsuits will make up for the massive amount of money wasted for the performance losses

Re: Meltdown, aka “Dear Intel, you suck”

#74

Post by bonzini »

forgotpw2018 wrote: post #73
DougN7 wrote: post #40

I don’t understand the Intel hate. It’s not like their engineers are dumb or lazy. This exploit is very hard to imagine before now. And it’s there because chip makers were trying to wring out more performance. It’s unfortunate if anythig.

All other chipmakers are 'immune' to Meltdown precisely because the attack is obvious. Cache timing is hard, but speculating execution before checking permissions is plain dumb. If it was such a mythical attack why doesn't it work on anyone else's chips? Intel screwed up hard on this and I have no sympathy. Hopefully the incoming lawsuits will make up for the massive amount of money wasted for the performance losses

The most recent ARM chips (cortex A75) are vulnerable.

Re: Meltdown, aka “Dear Intel, you suck”

#75

Post by xucheng »

emn13 wrote: post #70
xucheng wrote: post #61

Earlier quoted context omitted.

I think there is another important reason to extend embargoes aside preparing patches. Vulnerabilities like Meltdown and Spectre are in fact a whole new family of attack methods. It would take time to fully evaluate the extent of the problem. I would not be surprised that we learn new variants of Spectre in the coming future.

These classes of attacks are not new. Timing attack in crypto have been widely used for a long time. And even specifically in CPU's there was stuff like http://www.daemonology.net/papers/htt.pdf and http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.190... over ten years ago(!) . To quote that last paper: > We show how processor architecture features such as simultaneous multithreading, control speculation and…

Yes, I am aware of them and agree with you. In fact, cache-miss side channel attacks are known by academics for years as well. However, this is the first time someone combining various of previous techniques (timing, cache-miss, speculative loading etc.) together to make this attack work.

Quote from the meltdown paper:

> We expect that Meltdown and Spectre open a new field of research to investigate in what extent performance optimizations change the microarchitectural state, how this state can be translated into an architectural state, and how such attacks can be prevented.

So we won't see the last of Spectre.

Re: Meltdown, aka “Dear Intel, you suck”

#76

Post by tomxor »

apcragg wrote: post #68
emn13 wrote: post #54

Earlier quoted context omitted.

Spectre is somewhat reasonable; at least some variants are forgivable. Meltdown isn't. The risks due specifically to speculation and cache timing attacks (and lots of related stuff) were well known and documented for over a decade. They shouldn't have been speculating across memory protection boundaries, and they should have known that - even if it was unclear exactly how one might exploit such information leakage.

If it is so well known why has it taken 20 years to be discovered?

I don't know for sure but i'm guessing it's because this is all proprietary stuff, security researchers working on closed source hardware have to to a lot of inference... turn an already difficult theory into practice on an obscured implementation that is substantially harder to reverse engineer than compiled code.

Re: Meltdown, aka “Dear Intel, you suck”

#77

Post by crankylinuxuser »

laurencei wrote: post #66
mintplant wrote: post #65

Earlier quoted context omitted.

> This exploit is very hard to imagine before now. It's really not. It's the sort of thing you wonder after first learning about out-of-order and speculative execution in a computer architecture class, but your professor assures you that implementors have been very careful to ensure any partial execution is properly flushed and rolled back. Then it turns out that, nope, no one's actually been keeping an eye on this a…

...but if it is "so obvious" - why has it taken ~20 years to discover it (publically)?

Because like most inventions, its obvious after the fact. But getting there was time-intensive and wrought with many ways of failure.

Re: Meltdown, aka “Dear Intel, you suck”

#78

Post by mtgx »

kowdermeister wrote: post #9
ksec wrote: post #4

May be time for OpenBSD people ( if they have the resources ) to build a CPU from ground up with RISC-V?

Just crowdsource a few billion $ for R&D and we are good to go.

I don't know if you're joking, but that may not even be an impossible task if say OpenBSD were to create a cryptocurrency for their OS, as long as they tried to make it as legal as possible and try to see it more like a crypto-asset/stock kind of thing than a "digital ponzi scheme."

Seems to have worked for the IPFS guys (I'm talking about existing projects that only launched a cryptocurrency later on, rather than from the start). Brave's BAT qualifies for that, too.

Re: Meltdown, aka “Dear Intel, you suck”

#79

Post by forgotpw2018 »

bonzini wrote: post #74
forgotpw2018 wrote: post #73

Earlier quoted context omitted.

All other chipmakers are 'immune' to Meltdown precisely because the attack is obvious. Cache timing is hard, but speculating execution before checking permissions is plain dumb. If it was such a mythical attack why doesn't it work on anyone else's chips? Intel screwed up hard on this and I have no sympathy. Hopefully the incoming lawsuits will make up for the massive amount of money wasted for the performance losses

The most recent ARM chips (cortex A75) are vulnerable.

Didn't know that. The chipmaking business is insular and pretty incestuous, I wonder if the same engineers built both speculative execution units.

I've got a friend in CPU design and he's only got about 50 companies he can work for in the world where he could do the same job he does now

Post reply on HN