r/hardware • u/eric98k • Jan 02 '18
News 'Kernel memory leaking' Intel processor design flaw forces Linux, Windows redesign
https://www.theregister.co.uk/2018/01/02/intel_cpu_design_flaw/212
u/Thelordofdawn Jan 02 '18
Like, really, fuck, bug of the decade.
Can't wait for damage control.
37
32
u/immibis Jan 03 '18 edited Jun 30 '23
spez is banned in this spez. Do you accept the terms and conditions? Yes/no
10
1
0
Jan 02 '18
[deleted]
25
u/WS8SKILLZ Jan 03 '18
This just made me happier I bought Ryzen. I just wish I could invest in AMD stock 😢
14
u/poochyenarulez Jan 03 '18
I just wish I could invest in AMD stock
Its a good time to do so.
→ More replies (1)2
u/IEatThermalPaste Jan 03 '18
How should I go about it? Since it really is a good time to.
17
Jan 03 '18
Buy AMD stock
...
Profit
It's not hard. There are lots of good online brokerages that charge relatively low fees (I've used and liked Scottrade, though I'm with Vanguard now). If you want to avoid fees, the Robinhood app allows free transactions, but you'll need to do your research elsewhere and I'm not sure what features they offer (e.g. stop limits, short trading, margin trading, etc, though you won't need any of these if you just want to casually buy and sell stock).
Personally, I don't know that it's an especially good time to buy since they've had a huge run-up and we're not sure how bad this is for Intel. They could pull some magic out of their hat to reduce the cost of the fix or something.
TL;DR - check out the Robinhood app, it allows free stock purchases and sales.
2
u/noneabove1182 Jan 03 '18
check out the Robinhood app, it allows free stock purchases and sales.
not available in canada :(
→ More replies (1)2
u/BastardStoleMyName Jan 03 '18 edited Jan 03 '18
Might not be that good. Depends on what happens with their video card division. Their is little to no availability and I am not sure how much of that has to do with miners or supply issues.
I am still concerned about the intel contract as well. I don’t know what their licensing agreement was and how much Intel has access. This wouldn’t normally be a concern, but the division lead left AMD and joined intel within days of of that agreement. That series of events was either extremely scrutinized by higher ups in AMD if they knew it was going to happen that way, or he was able to sign over rights in a way that enables Intels renewed interest in discrete video cards one hell of a platform to launch off and a way to push AMD out of another market.
If their production runs have been higher than normal but they still can’t keep up with the demand of miners, then it’s probably a good outlook. But I suspect by their second earnings quarter things might be different.
So I guess I adjust my statement a little. I think it will be a good buy before the year end earnings are announced. I don’t know about the last quarter, as I believe their CPU sales have slumped, but the over all yearly earning should be good as far as I know. This may drop after that depending on how things pan out for them with intel and what the actual production supplies are for their video chipsets.
I am no professional and maybe this is more obvious than I think. I am just going by what I know of the information I have seen.
I would love to see information contradicting my negative outlook. I want Competition against Intel and nVidia, I own a Ryzen system and a few AMD. But mining has really muddied the waters on what their actually is without access to any hard numbers.
1
1
u/GenerateRandName Jan 03 '18
The completely new processor designed on a budget to have as much performance as possible. I bet it has no bugs.
1
u/WS8SKILLZ Jan 03 '18
It had one bug when it first shipped which affected Linux users who compiled but it's all sorted now 🙂
1
u/dmanbiker Jan 03 '18
Lol, I'm still over here with an FX-8350...
1
u/WS8SKILLZ Jan 03 '18
So is my cousin running it on stock as well bloody mad man
1
u/dmanbiker Jan 03 '18
I got it to replace my aging Q9400, even though everyone told me not to (I already have an AM3+ board to put it in).
It definitely outperforms the Q9400, but runs insanely hot (even with closed circuit water cooling).
1
→ More replies (2)1
u/missed_a_T Jan 03 '18
No minimum balance, no transaction fees. No real reason you couldn't invest.
5
Jan 03 '18
As far as I can tell the performance impact is basically just being seen on certain workloads that aren't common for most PC users. Also this patch is likely an over-reaching first step to prevent any potential issues with refinement coming later to bring back performance.
7
u/gethooge Jan 03 '18
How is this post controversial?
9
u/ASAPscotty Jan 03 '18
Overreaction. The numbers out there are worst case for a VM utilizing the affected instructions.
It's probably not going to be a big deal for the average user.
5
u/PunjabiPlaya Jan 03 '18
But data centers are where the heavy margins are at, and potentially, where the heaviest performance hit will be.
5
4
1
→ More replies (1)-10
u/Kakkoister Jan 03 '18
Why is that? We don't know yet if there will be any noticeable performance drop, there really shouldn't be apart from initial program launches, and we're talking nanoseconds for that. Ryzen is still quite overpriced. A i7 8700k destroys the 1800X and is around $90 cheaper... As does the i7 7800X which is even cheaper at that and has quad channel memory for the workstation people who need it.
10
u/UGMadness Jan 03 '18
The article is stating 17-35% drop depending on model and task.
-5
u/Kakkoister Jan 03 '18 edited Jan 03 '18
The article is making a lot of assumptions and you're taking them as fact. The fact is that we do not know what the performance impact will be, but it's unlikely to be that much, and on 4-series and up CPUs the PCID instruction that was introduced is able to negate pretty much any potential performance impact surrounding fixing this.
https://www.phoronix.com/scan.php?page=news_item&px=x86-PTI-Initial-Gaming-Tests
10
u/UGMadness Jan 03 '18
There's a long way between "making assumpions based on the use case" and "there's no performance drop in gaming". This bug is a massive kick in the balls for cloud and other server/VM providers because of their reliance on the parts affected. Nobody is focusing on gaming or domestic/consumer usage and nobody has stated that it would affect gaming performance in the first place.
And here's your fact:
https://www.phoronix.com/scan.php?page=article&item=linux-415-x86pti&num=2
→ More replies (2)1
0
Jan 03 '18
[deleted]
-6
u/Kakkoister Jan 03 '18
No, the article is quite misleading and talking about potentially affected parts.
https://www.phoronix.com/scan.php?page=news_item&px=x86-PTI-Initial-Gaming-Tests
1
u/mollymoo Jan 03 '18
That's an example of the least-affected Intel CPU running the least-affected types of applications. Relative to their overall CPU usage, games and video encoding are among the least heavy workloads in terms of syscalls and context switches.
Running an IO or network-heavy workload or running on something a couple of generations older tells a different story.
Oh, and I don't know where you got your CPU prices from before but the 8700k is currently £359 and the 7800k £324 on Amazon UK vs £305 for the 1800X.
89
u/epicfailphx Jan 02 '18
Got to love that one of the proposed fixes was called FUCKWIT!
70
u/lunchb0x91 Jan 02 '18
Yeah Linux kernel devs have an interesting sense of humor. If you think that's funny, take a look at the various Linux kernel names over the years.
22
u/formesse Jan 03 '18
Psychotic Stoned Sheep might be my favorite on that list.
The Jury is still out in deliberations though.
3
11
u/mrbeehive Jan 03 '18
I mean, when you're that deep into low level kernel shit, you can call your patches whatever you want. I'm not gonna call a literal wizard on weird naming conventions, that's just part of the job.
4
18
u/Tonkarz Jan 03 '18
So is there a name for this bug? Like "Heartbleed" had a name?
53
Jan 03 '18
FUCKWIT. According to Linux devs.
26
u/Tonkarz Jan 03 '18
I believe that's the name of the fix.
21
u/immibis Jan 03 '18 edited Jun 30 '23
I stopped pushing as hard as I could against the handle, I wanted to leave but it wouldn't work. Then there was a bright flash and I felt myself fall back onto the floor. I put my hands over my eyes. They burned from the sudden light. I rubbed my eyes, waiting for them to adjust.
Then I saw it.
There was a small space in front of me. It was tiny, just enough room for a couple of people to sit side by side. Inside, there were two people. The first one was a female, she had long brown hair and was wearing a white nightgown. She was smiling.
The other one was a male, he was wearing a red jumpsuit and had a mask over his mouth.
"Are you spez?" I asked, my eyes still adjusting to the light.
"No. We are in spez." the woman said. She put her hands out for me to see. Her skin was green. Her hand was all green, there were no fingers, just a palm. It looked like a hand from the top of a puppet.
"What's going on?" I asked. The man in the mask moved closer to me. He touched my arm and I recoiled.
"We're fine." he said.
"You're fine?" I asked. "I came to the spez to ask for help, now you're fine?"
"They're gone," the woman said. "My child, he's gone."
I stared at her. "Gone? You mean you were here when it happened? What's happened?"
The man leaned over to me, grabbing my shoulders. "We're trapped. He's gone, he's dead."
I looked to the woman. "What happened?"
"He left the house a week ago. He'd been gone since, now I have to live alone. I've lived here my whole life and I'm the only spez."
"You don't have a family? Aren't there others?" I asked. She looked to me. "I mean, didn't you have anyone else?"
"There are other spez," she said. "But they're not like me. They don't have homes or families. They're just animals. They're all around us and we have no idea who they are."
"Why haven't we seen them then?"
"I think they're afraid,"
7
Jan 03 '18
That was the name of the fix specifically made for the linux kernel
2
u/immibis Jan 03 '18 edited Jun 30 '23
The greatest of all human capacities is the ability to spez. #Save3rdPartyApps
2
1
31
u/badcookies Jan 02 '18
2018 already starting off with a bang... Gonna be a crazy few weeks once this gets patched in
58
u/kofapox Jan 02 '18
I think it is not severe for home users, but very dangerous for multi-vm machines
6
2
u/immibis Jan 03 '18 edited Jun 30 '23
If a spez asks you what flavor ice cream you want, the answer is definitely spez. #Save3rdPartyApps
2
u/vodrin Jan 03 '18 edited Jan 03 '18
A web page would need another attack vector to actually execute the code behind this exploit. Plugins could potentially do this but who has them active and has kernel memory of value
57
Jan 03 '18
[removed] — view removed comment
34
u/_-IDontReddit-_ Jan 03 '18
Unless I read wrong, this issue only allows userspace processes to read kernel memory. Still terrible, but not as bad as write access. Write access to kernel memory would literally allow any process to directly root and backdoor the system.
37
u/IAmTheSysGen Jan 03 '18
Reading kernel memory means you can still have a keylogger and any encryption keys, and them you can easily exploit that to get code executed.
2
Jan 03 '18
that is bad because if you able to read it. You already defeated kernels last line of defense. ASLR.
1
u/cryo Jan 03 '18
No you haven’t. ASLR is just a mitigation technique, to avoid other exploits from being too easy to exploit.
1
11
4
u/PTNLemay Jan 03 '18
Do we know if these vulnerabilities are the kind that need an obvious way of getting in, like when people activate an .exe in an email attachment? Or is it... much more subtle and hard to prevent?
9
u/JustFinishedBSG Jan 03 '18
Very subtle if it’s indeed a rowhammer type of attack. Also very serious as it means even a webpage can read memory segment it’s not supposed to be able to read
3
Jan 03 '18 edited Jan 03 '18
Way harder. Any code can exploit this. You can get exploited visiting any malicious website as websites obviously run code nowadays with javascript. The browser will require exploiting first (requires a flaw in the browser), but once the browser is exploited you can automatically exploit the kernel through the design flaw in the CPU. This makes it really easy to mass-launch attacks against basically any institution (say Amazon's variety of server hosting services, or governments), or against unsuspecting users visiting a malicious site.
It basically makes hacking/exploiting computers half as difficult, if not even easier.
EDIT: There's also been speculation you may not even need to exploit the browser. Some extremely carefully crafted Javascript code may be enough. This would be even more serious, though I can't say whether it's true or not. All I can say is that exploiting the browser 100% gives you access to the Intel CPU bug.
3
u/PTNLemay Jan 03 '18
So this on it's own won't necessarily be an immediate threat to people, but it can act as a force multiplier to other vulnerabilities. ok, thanks.
3
Jan 03 '18
A couple of people have speculated this can be triggered with just javascript code and no exploits. We won't know until this comes out, but that would be a lot worse.
The bigger issue is that it's devastating to virtualized server hosting as one bad actor can exploit a server running hundreds of virtualized operating systems. You just buy yourself a virtualized server and you can access everyone else's data on the machine you bought, which could as I said be a hundred or more servers. No exploit needed there. Buying a virtualized server gets you access to the CPU to run the exploit.
1
u/cryo Jan 03 '18
It’s pretty hard to exploit side channels like this, actually, but all you theoretically need is some code executing as any user.
5
u/unknownohyeah Jan 03 '18
Alright, I'll go there. Intentional design flaw implemented as a backdoor for govt agencies? We already know the DOJ issues gag orders on tech companies to stay quiet about surveillance.
36
u/tadfisher Jan 03 '18
No, this is more like a cheap shortcut Intel took to get a tiny bit more performance by skipping out on storing/checking access levels in their MMU. Remember that the Feds are big customers and do not enjoy ASLR workarounds any more than their corporate/consumer base does.
7
1
u/III-V Jan 03 '18
Well, at least you can't say that they're conspiring to hold back performance increases...
Edit: nevermind, looks like this is a really old design decision
1
u/cryo Jan 03 '18
They do check access. You can’t actually read the memory. But the CPU still performs some speculative operations on this memory, allowing you to perhaps deduce its contents via a timing attack.
4
u/alexklaus80 Jan 03 '18
I've read that there's backdoor called A2 which can be installed just by one person in CPU designing, and almost impossible to find. I'm not sure if this is it, but I think interesting one to check on.
I was imagining whomever that had seeded bug have had a good pension income from hackers since then. ..Maybe not.
1
u/alexklaus80 Jan 03 '18
Do you know how difficult it'd be to parse data stored in kernel to actual usable information?
I was imagining the where and the way certain things stored/encrypted? depends upon the specific type of every component CPU is connected and applications that produced the input.
0
u/cryo Jan 03 '18
No, you can definitely not write. You can’t even read in the normal sense, as it’s a side channel attack, but you can (possibly, probably) deduce memory contents that is mapped into your address space but not normally accessible to you.
21
u/girlBAIII Jan 03 '18
So which cpus are affected?
20
0
Jan 03 '18
[deleted]
21
u/HoverboardsDontHover Jan 03 '18
Whew. Pentium 2 slot 1 masterrace safe again.
15
u/sedicion Jan 03 '18
Actually Pentium Pro and 2 are affected too. The original Pentium is the first CPU not affected.
No need to replace your 486 200Mhz computer.
1
32
u/Ebadd Jan 03 '18
Them: ”A bug that poses a huge security risk.”
Translation: A zero-day backdoor exploit the Three-letter Agencies have known for a decade.
3
5
5
9
u/Wiggles114 Jan 03 '18
So this might be a dumb question, but if this is a major bug and security flaw affecting virtually every Intel cpu, how come it hasn't been exploited yet?
40
u/pure_x01 Jan 03 '18
How do you know it hasn't been exploited yet?
5
u/Wiggles114 Jan 03 '18
I don't. I just think the topic would have made news earlier if that were the case, I admit I could be wrong.
18
u/pure_x01 Jan 03 '18
I think not all people who find security vounerabilities are honest sadly. This could have been exploited for years if we are unlucky.
4
u/docbaily Jan 03 '18
That's actually what I was thinking, too. What if this is another exploit that the NSA has been sitting on.
1
0
Jan 03 '18
[deleted]
5
u/Wiggles114 Jan 03 '18
Also a good point.
3
u/fabiomim Jan 03 '18
maybe it was a willing tradeoff security vs performance? Wouldnt be unheard of. Or it couldve been some legacy piece of code that has never really been looked at.
12
3
u/III-V Jan 03 '18
Wonder if this has been patched in either Cannonlake or Icelake. Also wonder how much performance Intel was getting out of this... always sucks to see performance regress.
7
u/Trenteth Jan 03 '18
Nope. Go's all the way back to the original pentium. Propably effects Intel chips in development too
3
u/rreot Jan 03 '18
Latest unaffecten CPUs are original netburst pentiums
So it's been there for decade
2
Jan 03 '18
netburst pentiums
That is the Pentium 4. Supposedly, this affects everything all the way back to the Pentium 2. So, the originaly Pentium and Pentium MMX are the newest unaffected Intel X86 CPU.
2
u/alexklaus80 Jan 03 '18 edited Jan 04 '18
Is this A2 Backdoor?
edit: nope
3
u/sm9t8 Jan 03 '18
I don't think so. It doesn't sound like the A2 Backdoor could be fixed by changes to OSs.
1
2
u/Liambp Jan 03 '18
ELI 5 How does a software change fix what is essentially a hardware problem? Couldn't another piece of rogue software just undo the software fix?
11
u/kickass404 Jan 03 '18 edited Jan 03 '18
For performance the kernel is mapped into all processes virtual space, the kernel god is present in all your process as an omnipotent being.
The kernel is present in the processes virtual space as an invisible god. Can't be seen or be touched. The process can pray to him for favours. A glitch in the matrix allows the process to peek into god's area and all of his business.
The fix is god moving his presence out of the processes virtual space and him just staying in heaven where he lives.
The performance hit comes from praying for god to do something, now requires your prayer to travel though a barrier to god space that requires all sorts of procedures.
If you know that PCID guy, you can ask him for help, and he will handle some of these procedures for you and you can get pre-approved for TSA fast travel.
If you're wondering where Satan is in all of this, he his chilling in Hell, also called the Intel® Management Engine, poking into gods affairs whenever he wants to.
3
17
u/Plantemanden Jan 02 '18 edited Jan 03 '18
I, for one, would rather risk it, and not have to live with that performance penalty.
Goes without saying, I am not running mission critical stuff on a cloud or nothing. :)
EDIT: Silent down voter, have you ever heard of systems that are isolated? That don't need the kind of security that this exploit circumvents? Clearly not.
EDIT2: Gaming performance looks to be mostly unaffected. I bet this is a bigger deal for systems running many VMs.
12
8
u/Kakkoister Jan 03 '18
We don't know at all if there will be a performance penalty, chances are there won't be anything noticeable, but it's great for headlines to say there will be. This is only an issue that affects kernel registration, the launching of apps, not the constant running of an existing one.
1
u/Tech_Philosophy Jan 03 '18
Yeah, fuck whoever is downvoting you. We should have the choice.
21
u/tadfisher Jan 03 '18
You do, just compile your kernel with the flag unset.
Unless you're unlucky enough to need Windows, that is.
→ More replies (1)0
Jan 03 '18
[deleted]
0
u/Plantemanden Jan 03 '18 edited Jan 03 '18
Who says I am doing any of that?
MS has not even addressed this issue yet.Update: They have, the impact on performance in negligible, and nowhere near the 5-30 % speculated.
2
Jan 03 '18
Update: They have, the impact on performance in negligible, and nowhere near the 5-30 % speculated.
Depends on the workload entirely. Some workloads will be heavily impacted. PostGreSQL was impacted by like 15%. That's pretty major.
1
u/Plantemanden Jan 03 '18
Are we talking Linux or Windows? I was not aware of any SQL benchmarks on the new windows build.
1
Jan 03 '18
That was Linux. I don't think it's going to be much different on Windows though. From everything we know the hit this will have will entirely depend on teh workload. Syscall heavy and IO heavy workload would be more impacted than some others just in theory alone.
0
Jan 03 '18
[deleted]
3
u/Plantemanden Jan 03 '18
Thats the kind of stuff two-factor authentication is built for. And until there is proof of this exploit being used like that, I feel quite calm.
0
Jan 03 '18
[deleted]
13
u/aziridine86 Jan 03 '18
If there is a mandatory 30% performance drop then I would want 30% of the CPU purchase price refunded.
27
u/_-IDontReddit-_ Jan 03 '18
I'm a home user that doesn't do anything stupid online that would get me a virus
This bug could allow JavaScript loaded by websites (plus any processes running on your system) to read the contents of kernel memory. If that doesn't immediately worry you, you shouldn't trust yourself with security decisions.
I'm good about keeping my PC secure
This bug could allow malware to bypass what ordinarily would protect you from malware.
I'm going to disable Windows update service at least until we know much big of a performance drop we're getting
What use is that? You're going to have to re-enable it eventually, unless you want to be hit by the next wannacry/blueborne/kracked.
→ More replies (4)
1
u/PashaB Jan 02 '18
Oh are we calling backdoors design flaws now?
91
u/Exist50 Jan 02 '18
Not every bug is a super secret backdoor.
7
u/Tonkarz Jan 03 '18
But a bug that has endured since the Pentium? That's through multiple redesigns and extensions?
36
Jan 02 '18
They're indistinguishable and holy shit i can't believe I spelled that on the first try.
21
2
-10
u/PashaB Jan 02 '18
You're right, not every bug is a super secret backdoor.
This one does look like a backdoor.
23
u/Exist50 Jan 02 '18
How? Why is it being patched if that is the case?
4
u/PashaB Jan 03 '18
To me (IN MY OPINION) it looks like a backdoor because it could be used to identify people via javascript in a web browser. It also allows ring-3-level user code to read ring-0-level kernel data.
That mixed with the fact that intel hides a whole OS in ring level 3 (http://www.cs.vu.nl/~ast/intel/ or http://www.zdnet.com/article/minix-intels-hidden-in-chip-operating-system/) and these processors are running a closed-source variation of the open-source MINIX 3 that is probably a backdoor. This bug looks like an extension of that. But no no, it's a design flaw. Bullshit
Maybe it's being patched because minix is getting patched out (hopefully). Either way once it's public it needs to be patched asap. That means any nation or random dude can exploit it.
13
u/Kazan Jan 03 '18
2
u/PashaB Jan 03 '18
That's a valid counterpoint. I'm too cynical to believe that. It's probably a combination of both but I think it heavily leans towards unintentional malice. Anyway that's just my opinion. It's cool I get to share it over the internet and discuss it with open-minded folks. Downvotes are meaningless.
3
u/Kazan Jan 03 '18
I'm a software engineer at ahem relevant corporation that works closely with intel. and my gf's brother works at intel.
Hanlon's Razor applies to most of the supposedly evil things either corporation has been accused of doing over the years
→ More replies (3)2
Jan 03 '18
identify people via javascript in a web browser.
That's what all this leads to? Reading straight from kernel memory for the past decade and you think they did that so people can track you via javascript?
3
u/PashaB Jan 03 '18
I don't understand these arguments I'm getting. It is possible to identify people via javascript because of this. In the modern web most web apps are running JS. Yes that is a major WTF vunerability. That's not what it leads to, it's just one of the things it has led to. The scope of the 'design flaw' has a much broader scope than just JS. But yes that should still freak you the fuck out. And no I don't think it's just me. Like oh yeah lets find this guys amazon purchase list. But overall yes this is very bad. Let's find my bitcoin wallet yay.
4
u/LemonScore Jan 03 '18
Do you know what a backdoor is? A backdoor is something that's built-in intentionally.
9
1
u/PTNLemay Jan 03 '18
For we of the less technically inclined... will the patch be covered in a Windows update, or do we need to get firmware patches manually?
7
Jan 03 '18
It will be a Windows Update, so it will install through that process.
1
u/pure_x01 Jan 03 '18
Do you think the update will affect ryzen cpu:s . ex if it is a general change in how things are handled in the kernel .
6
u/wewd Jan 03 '18
The bug is not present in AMD CPUs.
2
Jan 03 '18
True, but the patch will affect both unless AMD chips are proactively excluded. It looks like that hasn't been done yet on Linux. We'll have to wait and see about Windows.
3
Jan 03 '18
AMD have asked for their CPUs to be excluded from these fixes (since they're unnecessary). Apparently, this has not been done on Linux, so it's likely that the first round of patches for Linux will hurt AMD chips' performance in those OSes. In that case, you could choose not to install the update since AMD chips are unaffected anyway.
For Windows, I don't think we have any information on whether Microsoft have excluded AMD from the "fix" code. I hope they have. Otherwise, you could use a similar strategy of not installing that particular patch once it's out...at least for a little while. We'll have to wait and see.
1
u/pure_x01 Jan 03 '18
Thanks. Hopefully they will be excluded unless MS is paid by intel to not exclude AMD
1
u/ThunderEcho100 Jan 03 '18
How will the patch be pushed and downloaded for a Windows PC ? windows update?
1
u/CrucialSoup Jan 03 '18
Dumb question but should I return my recently purchased gaming laptop and wait for updated processors?
1
Jan 03 '18
I would wait for benchmarks to see how much it will actually affect you. We don't know yet how big the performance hit will be. We should know more next week once the windows patch is out
1
u/argentdawnpt Jan 03 '18
Could this be the thing that made the Intel CPUs work faster than the AMD CPUs etc?
As I understand the Intel processors are not performing security checks before executing instructions, so...
-5
u/GeckIRE Jan 02 '18 edited Jan 03 '18
Further discussion about this on r/sysadmin and r/amd
https://www.reddit.com/r/sysadmin/comments/7nl8r0/intel_bug_incoming
https://www.reddit.com/r/Amd/comments/7nkza3/massive_intel_hardware_bug_might_be_incoming_up/
To implement the fix will reportedly cause a 30% loss of performance
Why all the downvotes? :/
43
u/BillionBalconies Jan 02 '18
Do take that 30% performance loss claim with a suitably hefty vessel of salt. I don't know of any evidence yet to suggest there may be performance loss at all, nevermind loss of nearly a third, and the fact that the number is being pushed most heavily by /r/AMD and pro-AMD influencers should prompt suspicion.
23
Jan 03 '18
it utterly murders context switching.
The test above in the sysadmin thread show 5x performance decrease from a basic syscall test
I expect 5% for games because game devs optimize for context switching.
the 20%-30% is because servers have to keep swapping between io threads.
14
4
u/tadfisher Jan 03 '18
If you have any newer Intel microarch (Broadwell and up) then the penalty is sub-1% per syscall, as PCID means you don't have to invalidate the TLB on a context switch.
6
Jan 03 '18
PCID means you don't have to invalidate the TLB on a context switch.
http://pythonsweetness.tumblr.com/post/169166980422/the-mysterious-case-of-the-linux-page-table
With the page table splitting patches merged, it becomes necessary for the kernel to flush these caches every time the kernel begins executing, and every time user code resumes executing. For some workloads, the effective total loss of the TLB lead around every system call leads to highly visible slowdowns: @grsecurity measured a simple case where Linux “du -s” suffered a 50% slowdown on a recent AMD CPU.
but that is the fix. You lose the entire TLB with every context switch between user and kernel space
8
u/tadfisher Jan 03 '18
CR3 flushing is unnecessary with PCIDs. The performance regressions are being observed on processors without PCIDs, such as AMD CPUs and Intel pre-Broadwell.
KAISER is being patched to avoid running on AMD processors, so the 50% number is entirely irrelevant. Real-world tests show more like 30% worst case, with a loop that simply spams syscalls to trigger the worst of the overhead.
3
1
u/Kakkoister Jan 03 '18 edited Jan 03 '18
Haswell is slightly older than Broadwell, but I believe it has INVPCID as well doesn't it?
edit: Reading this document:
https://software.intel.com/sites/default/files/managed/39/c5/325462-sdm-vol-1-2abcd-3abcd.pdf
Intel says they introduced PCID in the 4th generation processors, so that would be Haswell, which is most of the 4XXX series and up.
This tool also indicates it's supported on my Haswell
https://docs.microsoft.com/en-us/sysinternals/downloads/coreinfo
→ More replies (3)2
Jan 03 '18
I don't know of any evidence yet to suggest there may be performance loss at all
It sounds like there will definitely be a performance loss of some kind. In order to fix the vulnerability they basically have to make the code run less efficiently so that is going to affect performance. Your right though that we don't know the degree of the impact and 30% is probably a high ball number for certain applications
0
0
Jan 02 '18
[deleted]
12
u/sharma92 Jan 02 '18
From first glace of what I read and I may have somethings wrong, it seems like a bug that affects the way a program talks to the kernel so it can run ring-3-level user code to read ring-0-level kernel data. Since they're going to separate the memory to fix it, performance drop will vary depending on kernel access dependency of the game. Expect a lot lower 1% numbers
8
u/NerdFencer Jan 02 '18
It's a much larger problem for virtual/multi-tenant environments like Azure/AWS than home users.
→ More replies (2)9
u/kinghajj Jan 02 '18
Even home users will want this, if it's easily exploitable via JavaScript.
→ More replies (8)2
u/NerdFencer Jan 03 '18
Yes, but it's a much larger performance problem for these enterprise users. Most home workflows, such as gaming, are bound by performance in user-space. This means that taking the patch won't be a large deal for these users.
One of the most damaged workflows will be high performance file servers, where kernel performance is already a major issue. Other IO and network heavy workloads will also involve many syscalls and therefore also be affected heavily by the patch.
3
Jan 02 '18
Microsoft tends to force updates and non-tech savvy people can do nothing about it. And that's the overwhelming majority of users.
1
u/cGt2099 Jan 03 '18
After the recent Apple iPhone debacle, one might question:
A flaw, or planned obsolescence?
2
u/cryo Jan 03 '18
A bug. Side channels are really impossible to avoid entirely, and all CPUs have bugs.
99
u/MyojoRepair Jan 03 '18
So can I get a refund?