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The mysterious case of the Linux Page Table Isolation patches

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Re: The mysterious case of the Linux Page Table Isolation patches

#251

Post by emilfihlman »

userbinator wrote: post #37
avian wrote: post #33

Earlier quoted context omitted.

Why would users refuse to buy hardware that works 99.9999999999% of the time when they apparently have no problem buying software that works 99% of the time? Radioactive decays and cosmic particles flipping bits give an upper bound for reliability. You are not going to see low-background packages and rad-hard chips in your iPhone.

Radioactive decays and cosmic particles flipping bits give an upper bound for reliability well below 99.9999999999% If it works 99.9999999999%, then it has a failure rate of 0.0000000001%, or 1E-12. Considering that a modern CPU executes approximately 1E9 operations per second, and that regular HDDs have a worse-case BER of 1 in 1E14 bits, 1E-12 is actually rather horrible and the actual error rate of computer hardwa…

This is not how probabilities work but eh.

Re: The mysterious case of the Linux Page Table Isolation patches

#252

Post by bitexploder »

slackingoff2017 wrote: post #167
justincormack wrote: post #151

Looks like it is speculative execution based, and does not affect AMD https://lkml.org/lkml/2017/12/27/2 AMD processors are not subject to the types of attacks that the kernel page table isolation feature protects against. The AMD microarchitecture does not allow memory references, including speculative references, that access higher privileged data when running in a lesser privileged mode when that access would resu…

maybe it has to do with CR3 register? https://patchwork.kernel.org/patch/10138835/ Edit: switched to link without AD cancer

I think they are just using the CR3 register to implement the fix. The actual side channel will be something a bit more esoteric.

Something like this: https://cyber.wtf/2017/07/28/negative-result-reading-kernel-...

Re: The mysterious case of the Linux Page Table Isolation patches

#253

Post by pixl97 »

hintss wrote: post #245
pixl97 wrote: post #155

Earlier quoted context omitted.

Eh, that information is shared widely. Some decent googl-fu will get you the information you want. The difference is a lock-pick can't exploit 20,000 doors in 20 minutes.

There are definitely bypass tools for common lock mechanisms, whose mechanism of operation isn't readily google-able.

And you still have to visit those, one at a time, in person where things like getting shot could occur.

Re: The mysterious case of the Linux Page Table Isolation patches

#254

Post by VectorLock »

snom380 wrote: post #123
vitaliyf wrote: post #113

This may or may not be related, but there is a Xen advisory embargoed until Thursday (see https://xenbits.xen.org/xsa/ ) and I am aware of at least one VM provider who scheduled emergency VM reboots across their entire fleet this week because the issue cannot be addressed through hot-patching.

I got around 10% of our Xen instances scheduled for reboot on Jan 4th, mostly long running instances. It's the first time I've seen that many instances scheduled at once.

Also got a large number of instances with scheduled reboot on Jan 4th in older AZs.

Re: The mysterious case of the Linux Page Table Isolation patches

#256

Post by dghughes »

dghughes wrote: post #60
jerrysievert wrote: post #18

Earlier quoted context omitted.

not sure on exact details, but I received one as well, on a free-tier account I had sitting around with an empty dynamodb table that was showing very high projected usage. it was enough that I logged in immediately thinking that account had been hacked. nope, still empty table, deleted it and went to bed. glad I wasn't the only one who got that.

Same here. Mine was on standby so I terminated it. I wasn't sure what was going on so I nuked everything cancelled my account and will hope for the best.

Amazon sent me an email this morning (Jan 3, 2018) to say I have a bill but I had already cancelled my free account. I can't see what I owe (hopefully zero dollars) because my account is now non-existent.

One tiny Ubuntu instance I barely used and then put on standby. Then terminated.

Ugh :(

Re: The mysterious case of the Linux Page Table Isolation patches

#257

Post by revelation »

cjbprime wrote: post #19
revelation wrote: post #7

No ones hiding anything, this patchset was developed in the open for many many months. The hysteria and intrigue in this random tumblr blog is completely superfluous. It's a hardware bug anyway. Here is a good hint to when something is not being embargoed: there is a paper and a public demonstration.

Will you apologize for saying this if an embargo is lifted? It seems very likely to me that there is an embargo.

Looks like I'm apologizing. Sorry, I was wrong.
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