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Intel Confronts Potential ‘PR Nightmare’ With Reported Chip Flaw

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Re: Intel Confronts Potential ‘PR Nightmare’ With Reported Chip Flaw

#351

Post by [deleted] »

DannyB2 wrote: post #72
rayiner wrote: post #52

Can someone help me understand why this is such a big deal? This doesn’t seem to be a flaw in the sense of the Pentium FDIV bug where the processor returned incorrect data. It doesn’t even seem to be a bug at all, but a side channel attack that would be almost expected in a processor with speculative execution unless special measures were taken to prevent it. And it doesn’t seem like it can be used for privilege esca…

There is this thing called "return oriented programming". You write your program as a series of addresses that are smashed onto the stack through some other type of vulnerability. When the current function returns, it returns to an address of your choosing. That address points to the tail end of some known existing function, such as in the C library and other libraries. When the tail end of that function returns, it…

[deleted]

Re: Intel Confronts Potential ‘PR Nightmare’ With Reported Chip Flaw

#352

Post by bandrami »

vardump wrote: post #89
ashelmire wrote: post #81

Earlier quoted context omitted.

From what I've read, this slowdown only affects syscalls, which, since they aren't usually a huge percentage of processing in the first place, should not have such an effect. You're more likely looking at a few percent at most, which is not going to be enough to make AMD outperform Intel. Let's stop the fear mongering and wait for actual metrics.

> From what I've read, this slowdown only affects syscalls Incorrect. It also affects interrupts and (page) faults. Any usermode to kernel and back transition.

That 100Hz timer tunable just got a lot more attractive...

Re: Intel Confronts Potential ‘PR Nightmare’ With Reported Chip Flaw

#353

Post by jshelly »

DannyB2 wrote: post #72
rayiner wrote: post #52

Can someone help me understand why this is such a big deal? This doesn’t seem to be a flaw in the sense of the Pentium FDIV bug where the processor returned incorrect data. It doesn’t even seem to be a bug at all, but a side channel attack that would be almost expected in a processor with speculative execution unless special measures were taken to prevent it. And it doesn’t seem like it can be used for privilege esca…

There is this thing called "return oriented programming". You write your program as a series of addresses that are smashed onto the stack through some other type of vulnerability. When the current function returns, it returns to an address of your choosing. That address points to the tail end of some known existing function, such as in the C library and other libraries. When the tail end of that function returns, it…

My BTC wallet feels more vulnerable then ever

Re: Intel Confronts Potential ‘PR Nightmare’ With Reported Chip Flaw

#354

Post by bluedonuts »

Brockenstein wrote: post #218
kylehotchkiss wrote: post #191

Does anybody know if the 30% performance reduction would apply to Macbook pros from within the past 2 years?

They run Intel CPUs made within the last ten years so would be subject to this issue. But the performance hit is really dependent on the computing that you're doing. It's not a guaranteed 30% or a guaranteed 5%. Are you doing a lot of really CPU intensive tasks that make a lot of syscalls? Most people aren't. If you are, you'll probably feel that pain. And if you're not, you probably won't notice a difference. And if…

Do we know that the kernel used in OSX is vulnerable at all? I haven’t found any discussion of it.

Re: Intel Confronts Potential ‘PR Nightmare’ With Reported Chip Flaw

#355

Post by monocasa »

panarky wrote: post #244
mtanski wrote: post #145

Earlier quoted context omitted.

As I mentioned in the other thread yesterday database and database like applications are going to be hit particular hard. Even more so on fast flash storage. Double whammy compared to apps just doing network IO. And while databases try to minimize the number of syscalls they still end up doing a lot of them for read, writeout, flush.

How would you trade this knowledge? Intel has already dropped and AMD is up. Maybe there's more to move, but first-order effects are at least partially priced in already. But what about second-order effects? Seems like virtualization should be vulnerable (VMWare and Citrix), but maybe they actually benefit as customers add more capacity. Software-defined networking and cloud databases should also suffer though it's u…

SDN might actually be OK. On the high-end they bend over backwards to not enter the kernel at all anyway, using stuff like DPDK. They stopped even using interrupts years ago.

Re: Intel Confronts Potential ‘PR Nightmare’ With Reported Chip Flaw

#356

Post by Houshalter »

rbanffy wrote: post #270
dsign wrote: post #19

This is a clusterf /big deal. Beyond the security implications, it means that all companies paying for computing resources will have to pay roughly 30% more overnight on cloud expenses for the same amount of CPU, assuming that they can just scale up their infrastructure. I know that bugs happen and that there was nothing intentional on this one, but at times like this is hard to held at bay the temptation of claiming…

It's a good thing CPU is fairly compressible. Unless you meter it very carefully, you'll see the performance hit and it'll not impact you that much. Very few of my physical boxes are over 70% CPU utilization on a daily average. It's, however, really bad if you sell CPU cycles for a living. You just lost between 5 and 30% of your capacity. If you have a large building, you just lost part of your parking lot to the Int…

Their competitors are also affected.

Also a 30% decrease is also equivalent to setting Moore's law back 7 months. A 5% loss is only setting it back 1 month. I know that's a bit of a naive calculation. But the point is computing power has long operated in an exponential domain. So big differences in absolute numbers aren't necessarily a big deal.

Re: Intel Confronts Potential ‘PR Nightmare’ With Reported Chip Flaw

#359

Post by chrisper »

nopriorarrests wrote: post #256

Can anyone with better knowledge ELI5 to me -- to fix this bug, are cloud providers have to patch only hypervisor machines, or guest boxes as well? And if fix is applied to hypervisor, will performance degrade on guest boxes as benchmark suggests? Thanks!

Yes it will affect your VM as it's the host CPU that's affected.

Re: Intel Confronts Potential ‘PR Nightmare’ With Reported Chip Flaw

#360

Post by crimethink2017 »

edraferi wrote: post #314
adornedCupcake wrote: post #306

Earlier quoted context omitted.

Why?

More diverse population—> lower trust —> less social will to support each other.

This might well be true, see e.g. [1]. An obvious irony is that those who are most happy with Intel's "velocity"-led culture, and the more general lack of diversity in the x86 CPU market, are probably also the most likely to reject this idea (that human diversity might have negative effects) outright.

____

[1] https://www.mpg.de/19440/Diversity_interaction_solidarity

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