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Meltdown Update Kernel doesnt boot

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Re: Meltdown Update Kernel doesnt boot

#141

Post by steveklabnik »

pubby wrote: post #106
drb91 wrote: post #99

Earlier quoted context omitted.

It does if you have something at 0x0. Or, to put it another way, I have no clue to what you're referring--what do references have to do with "The Billion Dollar Mistake"[0]? [0]: https://en.wikipedia.org/wiki/Tony_Hoare#Apologies_and_retra... EDIT: my apologies, that joke was actually pretty good.

What modern systems even map memory to 0x0? Doing so breaks the C standard, among other things.

http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc....

> On system reset, the vector table is fixed at address 0x00000000.

Also, I'm not an expert on the C standard, but in my understanding, it doesn't "break" it. That is:

* Address 0 and the null pointer are distinct

* A 0 literal treated as a pointer is guaranteed to be the null pointer

* The null pointer is not guaranteed to be represented by all zero bits

* If you get a pointer to address zero via pointer math or by other means than a 0 literal, you can still access address zero.

Re: Meltdown Update Kernel doesnt boot

#142

Post by collinmanderson »

deathanatos wrote: post #129
collinmanderson wrote: post #110

Earlier quoted context omitted.

Intel would just say it functions exactly as designed. :) (because it's a design flaw)

They did say that: > Intel and other technology companies have been made aware of new security research describing software analysis methods that, when used for malicious purposes, have the potential to improperly gather sensitive data from computing devices that are operating as designed. > […] > Recent reports that these exploits are caused by a “bug” or a “flaw” and are unique to Intel products are incorrect. ( ht…

Right, right. And they'll just keep saying it. :)

Re: Meltdown Update Kernel doesnt boot

#143

Post by dingo_bat »

arcticbull wrote: post #52
lunorian wrote: post #25

Earlier quoted context omitted.

Sorry fam - security issues are more important ¯\_(ツ)_/¯

I think it's fair to say build 108 has no security issues :P in fact, it's the most secure one yet.

Yup. It's so secure that they don't even load userspace into RAM!

Re: Meltdown Update Kernel doesnt boot

#144

Post by katastic »

gkya wrote: post #20

Would this entire Meltdown/Spectre thing count as the biggest mess-up of computing history? When yesterday the PoC repo was posted here, the spy.mp4 demo video gave me some chills. And now I can't update my OS before making an installation USB because Canonical can't just follow Linus' releases. Thanks.

I think Y2K had more practical impact across the business world. There was genuine fear that it could cause an actual apocalypse with all major computerized systems failing, medical machines killing people, banks being affected and all money and debts disappearing overnight.

It wasn't that bad, because people took it seriously. But there were still tons of practical systems affected and billions of corporate dollars associated with fixing it.

So when you say "biggest mess up" you gotta define specific qualifiers. Because Meltdown/Specter is going to be solved by simply... buying a new CPU. (And retrofitting the old ones). So it consist of mostly a patch.

A BIG important patch, granted. But it's still just a patch. But some ATM's aren't going to start spewing money like they did on Y2K.

Re: Meltdown Update Kernel doesnt boot

#145

Post by lathiat »

trendia wrote: post #61

(Copying my instructions from another post). If kernel 4.4 doesn't work, I recommend compiling the 4.15 kernel. (Note, however, that you may need to apply a patch to NVIDIA drivers). I've done this on Ubuntu 16.04 LTS, 17.10, and Debian 8 so far this week. To compile, set CONFIG_PAGE_TABLE_ISOLATION=y. That is: sudo apt-get build-dep linux sudo apt-get install gcc-6-plugin-dev libelf-dev libncurses5-dev cd /usr/src w…

I wouldn't really recommend doing this, but if you really want to do this, it would probably be easier just to use the pre-spun mainline kernels: https://wiki.ubuntu.com/Kernel/MainlineBuilds

Re: Meltdown Update Kernel doesnt boot

#146

Post by Zakharov »

brokenmachine wrote: post #74
KallDrexx wrote: post #51

Earlier quoted context omitted.

I'm assuming if you know either common byte patterns or string patterns you might be able to figure out where the password string is being allocated and watch that area of memory for changes.

Not sure if Meltdown is the same, but I read that Spectre can recover memory at about 10kb/sec. So it wouldn't be very efficient to scan the entire memory for a known pattern. I suppose if there was an exploit targeted at a specific program, it would be possible to work out what location the secrets are stored in?

According to the paper, Meltdown can recover memory at about 500 kb/s

Re: Meltdown Update Kernel doesnt boot

#147

Post by eltoozero »

gkya wrote: post #20

Would this entire Meltdown/Spectre thing count as the biggest mess-up of computing history? When yesterday the PoC repo was posted here, the spy.mp4 demo video gave me some chills. And now I can't update my OS before making an installation USB because Canonical can't just follow Linus' releases. Thanks.

Link to spy.mp4?

Found it: https://www.youtube.com/watch?v=RbHbFkh6eeE

Re: Meltdown Update Kernel doesnt boot

#148

Post by [deleted] »

lathiat wrote: post #145
trendia wrote: post #61

(Copying my instructions from another post). If kernel 4.4 doesn't work, I recommend compiling the 4.15 kernel. (Note, however, that you may need to apply a patch to NVIDIA drivers). I've done this on Ubuntu 16.04 LTS, 17.10, and Debian 8 so far this week. To compile, set CONFIG_PAGE_TABLE_ISOLATION=y. That is: sudo apt-get build-dep linux sudo apt-get install gcc-6-plugin-dev libelf-dev libncurses5-dev cd /usr/src w…

I wouldn't really recommend doing this, but if you really want to do this, it would probably be easier just to use the pre-spun mainline kernels: https://wiki.ubuntu.com/Kernel/MainlineBuilds

[deleted]

Re: Meltdown Update Kernel doesnt boot

#149

Post by snuxoll »

nykolasz wrote: post #130

Waiting a few days to patch my own servers... Not sure what is more dangerous right now: applying these rushed patches or the vuln itself.

What distro are you running? I trust Red Hat to get kernel updates right the first time, I just patched externally facing servers and systems that handle PHI tonight with no issues (outside of one of my PostgreSQL servers showing a non-neglible increase in CPU usage, damnit Intel).

Of course, I also go into any updates with a rollback plan. ITIL sucks, but one thing it taught me was the value of well documented plans any time you make changes to production systems.

Re: Meltdown Update Kernel doesnt boot

#150

Post by snuxoll »

Whitestrake wrote: post #90
lunorian wrote: post #24

See this is why you wait a day or two before patching :)

If everyone waited a day or two before patching, this bug would simply be opened a day or two later than it was.

How hard is it to just boot an older kernel and rollback the default? Before I even thought about patching sensitive systems tonight the first thing our IT director asked was if I had a rollback plan. The answer? "Yes, boot old kernel, yum history undo [transaction id], reboot".

Always have a backout plan when doing upgrades, I'm just glad EL and derived distributions have an easy way to do it with yum's transaction history.

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