Massive security hole in CPU's incoming?Official Meltdown/Spectre Discussion Thread

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Panino Manino

Senior member
Jan 28, 2017
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I was thinking, it's possible to disable these mitigation, at least on Ubuntu? It's possible to disable and enable at will? Or most of these mitigation once they're activate there's no reverting back?
 

jpiniero

Lifer
Oct 1, 2010
15,177
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I was thinking, it's possible to disable these mitigation, at least on Ubuntu? It's possible to disable and enable at will? Or most of these mitigation once they're activate there's no reverting back?

You can turn it off, that's how Phoronix is testing it.
 

nicalandia

Diamond Member
Jan 10, 2019
3,331
5,282
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AMD Processors Expose Sensitive Data to New 'SQUIP' Attack

SGX, Intel’s supposedly impregnable data fortress, has been breached
yet again



Thankfully anything of worth that I had that could be stolen has already been taken by my Ex Wives...!
 

moinmoin

Diamond Member
Jun 1, 2017
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“An attacker running on the same host and CPU core as you could spy on which types of instructions you are executing due to the split-scheduler design on AMD CPUs.”
That's kind of a "Doh!" situation. Cores have their own schedulers, which are obviously shared for SMT on the same core. That's why disabling SMT (or not splitting threads of the same core among different users) has been best practice since when Spectre first appeared.

The bug that enables ÆPIC Leak is what is known as an uninitialized memory read, which occurs when memory space is not freed up after the CPU has finished processing it, causing old data to leak that is no longer needed. Unlike previous CPU bugs with names like Specter, Meltdown, Foreshadow, and RIDL/Fallout/ZombieLoad – which resulted from temporary runs that created side channels revealing private data – ÆPIC Leak is an architectural flaw that resides in the CPU itself.
SGX has been essentially dead for quite some time already, but still: ouch! I sure hope Intel put more thought into the upcoming SGX2.
 
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nicalandia

Diamond Member
Jan 10, 2019
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moinmoin

Diamond Member
Jun 1, 2017
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I also don't use Windows 11, keep Windows 10 up to date..


Beware: Windows 11-ready CPUs with VAES "susceptible to data damage", full CPU list here
Hm, as far as I understand it it's not really the VAES instruction that's broken (as all chips implementing VAES seem to be equally affected) but the way Windows 11 previously applied it that could be susceptible to data damage, by what appears to be saving some safeguarding that now has to be applied anyway and consequently leads to longer processing time.
 
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DrMrLordX

Lifer
Apr 27, 2000
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So . . . Skylake-SP? Cascade Lake-SP is 9th gen and IceLake-SP is 10th gen. On desktop that affects Coffee Lake, Kabylake, and Skylake.
 
Feb 4, 2009
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has this hole turned out to be an issue. Seems like it’s been quite a while and consumer equipment doesn’t appear to be impacted. How about data centers?
 

DrMrLordX

Lifer
Apr 27, 2000
22,039
11,644
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has this hole turned out to be an issue. Seems like it’s been quite a while and consumer equipment doesn’t appear to be impacted. How about data centers?

Golden Cove and Raptor Cove aren't in datacentres yet, so there's no way of knowing how these newer kernel versions will affect Sapphire Rapids or Emerald Rapids. For consumer desktop, I would expect savvy Linux users to disable the mitigations if they need extra performance. Especially if there are no known exploits in the wild based on the vulnerability(ies) meant to be mitigated by later kernel versions.
 

JimKiler

Diamond Member
Oct 10, 2002
3,559
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Meltdown and Spectre are two major security vulnerabilities that affect nearly all modern processors, including those from Intel, AMD, and ARM. These vulnerabilities can potentially allow attackers to access sensitive data such as passwords, encryption keys, and other private information stored in memory on affected systems.
Meltdown and Spectre are both related to the way that modern processors use speculative execution to improve performance. Speculative execution allows processors to predict the outcome of certain operations and execute them in advance, which can improve performance. However, it can also lead to the exposure of sensitive data through side-channel attacks.
The vulnerabilities were first discovered and reported by security researchers in early 2018. Since then, software and firmware patches have been released by various vendors and operating system providers to mitigate the vulnerabilities. However, the patches may have a performance impact on affected systems, and it is important to keep systems up-to-date with the latest security patches to protect against these vulnerabilities.
It is recommended to regularly update operating systems, firmware, and other software to protect against security vulnerabilities such as Meltdown and Spectre. Additionally, it is important to practice good security hygiene, such as using strong passwords and multi-factor authentication, to reduce the risk of data breaches and other security threats.

I heard breaking news that Abraham Lincoln has been shot!
 

moinmoin

Diamond Member
Jun 1, 2017
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I personally think all the voltage glitching exploits should get a separate thread since those require a degree of access simply not comparable to classical software exploits.
 

DrMrLordX

Lifer
Apr 27, 2000
22,039
11,644
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Interesting glitch, though it requires you to use $200 of hardware and to spend several hours fiddling with the hardware directly. In person.

Not exactly plundervolt now is it?
 

moinmoin

Diamond Member
Jun 1, 2017
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Could be juicy. Phoronix's Michael is already doing performance tests with the new microcode and wrote he'll publish news this weekend if performance is affected by this.
 
Jul 27, 2020
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*groan* My Coffee Lake i7-8850H Precision Laptop already boots a bit slow with Windows 11. I don't like the sound of this AT ALL.
 

Hitman928

Diamond Member
Apr 15, 2012
6,133
10,556
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New “Zenbleed” vulnerability announced. Effects up to Zen2 products. Can be exposed remotely and even drum within a virtual machine. Firmware patch to address the issue is available for Epyc systems, no ETA for patch on the consumer side.