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Microsoft disables Spectre mitigations as Intel’s patches cause instability

securityweek.com

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Re: Microsoft disables Spectre mitigations as Intel’s patches cause instability

#171

Post by riskable »

mehrdadn wrote: post #82
tialaramex wrote: post #52

Earlier quoted context omitted.

Yes, in principle what you've said about the Unix approach here is correct, if you upgrade one half of a system and not the other half and now they're talking different protocols, that might not work. But keep in mind that if your system can't cope with this what you've done there is engineer in unreliability, you've made a system that's deliberately not very robust, unless it's very, very tightly integrated (e.g. tw…

Aaaaaand here comes the Linux defending! OK... > But keep in mind that if your system can't cope with this what you've done there is engineer in unreliability It's weird that you're blaming my operating system's problems on me . "My system" is something a ton of other people wrote, and this is the case for pretty much every user of every OS. I'm not engineering anything into (or out of) my system so I don't get the "…

> I don't know about you, but it happens more often than I would like that I update Linux (Ubuntu) and, lo and behold, I can't really use any programs until I reboot. Sometimes the window rendering gets messed up, sometimes I get random error pop-ups, sometimes stuff just doesn't run.

This is less of an issue with Linux, per se, and more to do with proprietary video drivers.

I have multiple systems in my home with various GPUs. The systems running Intel and AMD GPUs with open source drivers don't have this problem. The two desktops with Nvidia GPUs have this problem whenever the Nvidia driver is updated.

I also had the same exact problem with my AMD system back when it was running the proprietary fglrx driver.

Re: Microsoft disables Spectre mitigations as Intel’s patches cause instability

#173

Post by beagle3 »

quietbritishjim wrote: post #136
beagle3 wrote: post #32

Earlier quoted context omitted.

There is a very fundamental difference between how Unix and Windows view open files: On Windows, once the file is open, it is that filename that is open; You can't rename or delete it; Therefore, if you want to replace a DLL (or any other file) that is in use, you have to kill any program that uses it before you can do that; And if it's a fundamental library everything uses (USER32.DLL COMCTL.DLL etc), the only effec…

This doesn't fully explain why a reboot is not required on Linux. If a *nix operating system updates sysfile1.so and sysfile2.so in the way you describe, then there will be some time where the filename sysfile1.so refers to the new version of that file while sysfile2.so refers to the old version. A program that is started in this brief window will get mixed versions of these libraries. It is unlikely that all combina…

> This doesn't fully explain why a reboot is not required on Linux.

Of course there is a theoretical possibility that this will happen; however, in practice, updates (especially security updates) on Linux happen with ABI compatible libraries. E.g. on debian/ubuntu

apt-get update && apt-get upgrade

Will generally only do ABI compatible updates, without installing additional packages (you need 'dist-upgrade' or 'full-upgrade' for that).

Some updates will go as far as to prevent a program restart while updating (by temporarily making the executable unavailable).

Firefox on Ubuntu is an outlier - an update will replace it with one that isn't ABI compatible. It detects this and encourages you to restart it.

All in all, it's not that a reboot is never required for linux theoretically - it is that practically, you MUST reboot only for a kernel update, and may occasionally need to restart other programs that have been updated (but are rarely forced too).

Re: Microsoft disables Spectre mitigations as Intel’s patches cause instability

#174

Post by speedie »

tjoff wrote: post #18

I lost many hours over this last week. The system was unable to boot and finally a thread on reddit came to the rescue ( https://www.reddit.com/r/techsupport/comments/7sbihd/howto_f... ). This actually made the system boot but there are some leftovers being installed on first boot that I've been unable to disable that also causes the system to be unable to boot. So now, the machine is running but as soon as it is res…

If if weren't such a bih issue , this would be actually funny . M$ funboys bashing linux over an Intel patch that's rendering winblows useless ? ffs ...

Re: Microsoft disables Spectre mitigations as Intel’s patches cause instability

#175

Post by peterwwillis »

rlpb wrote: post #109
mehrdadn wrote: post #82

Earlier quoted context omitted.

Aaaaaand here comes the Linux defending! OK... > But keep in mind that if your system can't cope with this what you've done there is engineer in unreliability It's weird that you're blaming my operating system's problems on me . "My system" is something a ton of other people wrote, and this is the case for pretty much every user of every OS. I'm not engineering anything into (or out of) my system so I don't get the "…

> ...but it happens more often than I would like that I update Linux (Ubuntu) and, lo and behold, I can't really use any programs until I reboot... Ubuntu developer here. This doesn't happen to me in practice. Most updates don't cause system instability. I rarely reboot. Firefox is the most noticeable thing. After updating Firefox (usually it's a security update), Firefox often starts misbehaving until restarted. But…

Ubuntu user here. Ubuntu is less stable than my second girlfriend, and she tried to stab me once.

Lately, every time my co-worker has updated Ubuntu, it has broken his system. He's like my canary in the coalmine. I wait for his system to not fall over before I will update mine.

Re: Microsoft disables Spectre mitigations as Intel’s patches cause instability

#176

Post by garblegarble »

vetinari wrote: post #67
thanksgiving wrote: post #29

Earlier quoted context omitted.

Speaking of which, why do so many things require reboot to update on Windows?

> Speaking of which, why do so many things require reboot to update on Windows? We are getting there on Linux too - with atomic or image based updates of the underlying system. On servers you will (or already) have A/B partitions (or ostrees), on mobiles and IoT too, some desktops (looking at Fedora) also prefer reboot-update-reboot cycle, to prevent things like killing X while doing your update and leaving your mach…

>macOS also does system updates with reboot, for the same reasons.

And speaking from experience, the recent macOS way of applying an update is absolutely insane - on my Macbook Pro (with the stock SSD with 3GB/sec read and 2GB/sec of write) a small system update can take 10+ minutes to install

Re: Microsoft disables Spectre mitigations as Intel’s patches cause instability

#177

Post by jlgaddis »

beagle3 wrote: post #144
mehrdadn wrote: post #127

Earlier quoted context omitted.

Really? Somehow procure a list of all libraries that were updated in a system update, go through each one, find out which program was using it, and kill that program? Every single time I update? You can't be serious.

Apt does this automatically for you on uphrade

"checkrestart" also exists (on some distributions) for exactly this same purpose.

Re: Microsoft disables Spectre mitigations as Intel’s patches cause instability

#178

Post by cesarb »

Valmar wrote: post #133
cesarb wrote: post #61

In a related development, there are proposed patches to the Linux kernel (not yet merged) to blacklist the broken microcode updates: https://www.spinics.net/lists/kernel/msg2707159.html That patch disables the use by the kernel of the new IBPB/IBRS features provided by the updated microcode, when it's of a "known bad" revision. Since Linux prefers the "retpoline" mitigation instead of IBRS, and AFAIK so far the upstr…

> In a related development, there are proposed patches to the Linux kernel (not yet merged) to blacklist the broken microcode updates Linus probably won't pull it until it's truly known to be stable, because of his attitude towards having decent quality code and not causing needless system instability. Without Linus... who knows what would have happened by now.

They are on the "tip" tree (https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/...), so they'll probably be sent to Linus as soon as the merge window opens (Linux 4.15 has just been released, so the merge window should open soon). I expect these patches to be on 4.16, and also to be backported to the stable releases (4.15.x and others).

But yeah, upstream Linux kernel development is taking it slow. As far as I can see, variant 3 mitigations (PTI) are already in, variant 2 mitigations are partially in (retpoline) and partially not (the microcode dependent ones), and variant 1 mitigations are still under discussion.

Re: Microsoft disables Spectre mitigations as Intel’s patches cause instability

#179

Post by speedie »

PerusingAround wrote: post #151

I'm amazed on how Intel's stock price still keeps going UP, despite all these problems... just WOW.

I tend to think it's because the folk who trade with stock very well know that these "issues" are actually features. I can also bet that that "grilling" they get from US government is not about the mess the chip flaws are doing , it's about why the "flaws" were publicly announced.
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