How come branch prediction seems so vulnerable to exploits? Both spectre and meltdown were also caused by branch prediction not working quite right.
The more steps in the instruction pipeline the more ways there are for there to be an error where some result doesn’t get erased when undoing stuff from the wrong branch. It’s basically like telling someone to move into a new house and get settled then stopping them six hours in and trying to make sure you get all their stuff out.
It wasn’t branch prediction alone, it was the cache combined with branch prediction. The problem is that even discarded outcomes fill the cache with data. Those older vulnerabilities also had the problem that the access permissions check was done after the branch prediction. It’s probably too expensive to do when it’s not even clear yet whether the branch is going to be taken (that’s just speculation on my part though).
(that’s just speculation on my part though).
I see what you did there, even if you didn’t :)
Is there any information on the performance impact of the microcode fix or is it too early for that?
So far the word is the microcode fix causes negligible performance impact, but using the MSR fix causes 5-15% loss. In my own testing on EPYC hardware, microcode made no noticable difference to my workloads and benchmarks. Same as random noise in results.
Makes me glad I’m using an ancient CPU from before the vulnerability.
Which one?
From Wikipedia:
Google has reported that any Intel processor since 1995 with out-of-order execution is potentially vulnerable to the Meltdown vulnerability (this excludes Itanium and pre-2013 Intel Atom CPUs).
A Ryzen 2500U.
Welp. Thankfully my current AMD desktop PC will be the last one I’ll be using in my whole lifetime – RISC-V 4va. :^)
Updated amd64-microcode for EPYC processors appears available for several distributions which has mitigations available. I went ahead and proactively grabbed the microcode update from Debian unstable (not the best practice) and applied it without issue to my Bullseye/EPYC.
This isn’t exactly condoned as it’s not officially a backport, but I’ll take my chances as this is pretty critical.
Date of the updated microcode should be July 19th.
Why is it that every time there’s drama about hardware, its something I own?
That’s because of monopolies… There are only two brands of PC CPUs you could own…
That’s a duopoly and is also not true, there are ARM processors readily available outside of Intel and AMD.
Oh how I miss Cyrix
I feel really lucky that it doesn’t affect Zen 3 since that’s what I have lol but I’m sure they will find some similar bug for Zen 3.
Isn’t EPYC just a different name for Zen 3?
Nope, EPYC is their server processors, not their consumer processors.
Oh Nice! Well then I’m lucky too. Got a Ryzen 9
Well, this happens to affect the Ryzen 5 3600, which I’m pretty sure is one of AMD’s most popular processors ever…so you’re certainly not alone.
affects all Zen 2-based Ryzen, Threadripper, and EPYC CPUs
I know they’re probably pretty common, all my stuff ended up being Zen 3. Here’s hoping they don’t find similar issues in later generations.
I’ve got an older 3900X that’s Zen 2, but I’m otherwise clear, too.
It’s kind of hard to figure out which Zen # a CPU falls under, so here’s the Wiki page listing all Zen 2 CPUs.
Nice to know that security researchers are giving AMD some love too. Ill be sure to turn the patch off on my 3600 once it rolls around (can’t be losing any frames for something silly like security)
That’s a very bad idea.
The bad news is that the exploit doesn’t require physical hardware access and can be triggered by loading JavaScript on a malicious website.
I think it was sarcasm.
I want to say that I know, but it’s the internet, so you can never be sure. ¯\_(ツ)_/¯
Hell yeah, brother! 🤙
Oh poop.
This is not a back-end at all…
Linux has a merged mitigation so when the new kernel comes out Linux users will be safe
when the new kernel comes out Linux users will be safe
It’s going to take a lot longer than that for most distros to move to latest upstream. This specific fix might be pulled in as a hotfix if you’re lucky, but it still takes time. The latest Ubuntu LTS is on 5.15, for example, which was released in October 2021. Debian Bookworm, which just released last month, uses 6.1 from December 2022.
This is exactly the kind of thing that gets backported to stable LTS distros tho. The kernel Major.Minor is just the base - it doesn’t tell the whole story.
Right - I was just objecting to the suggestion that once upstream has the fix, “Linux users will be safe”.
Critical security fixes are backported. There where a lot of kernels released yesterday that had the fix. For 5.15, 5.15.122 was released with the zenbleed mitigation.
5.15.122 was released with the zen bleed mitigation
But Ubuntu users (for example) won’t get that automatically. Canonical still has to pull the upstream release, run validation, and roll out a patch. It will probably be speedy, but still on the order of several weeks before people see it by default.
Thank goodness I’m on arch (btw).
Looks like I’m getting the final kick to Linux on my main gaming PC.
Welcome to the club! We’re dozens here!
on my main gaming PC
good luck with that
Pop os on my gaming rig, works fine
Not sure if you are joking but Linux gaming is great now. I’ve been gaming for at least the last two years on only Linux. Check out https://www.protondb.com/explore
There hasn’t been a single game I’ve struggled to run in the last few months on proton. I haven’t had a windows PC in like a year ish or more?
I play games heavily too.
Try it out sometime if your setup isn’t extremely niche and maybe you’ll find it to be accommodating.
The weirdest things I’ve had to do are click a box in steam to enable proton usage and reinstall something in Lutris for Battle.net on world of warcraft.
I have yet to find a game that doesn’t run
At this point I don’t even check before buying
I know it’s not the best, but Proton has come a long, long way. I can play D4, Monster Hunter, factorio, lots of stuff.
I’ve been testing the waters with my steam deck. There are some hiccups, but almost everything I want to play can be done with proton.
It is really fantastic. With steam almost all the games i bother playing just works. Deleted the windows partition years ago.
Just have to check the community forum how well it works before buying. Or just get a refund if it does not work.I know it’s not the best
Didn’t pay thousands for top of the line ryzen and nvidia gear for “not the best” gaming situation.
Linux falls short on two major fronts, less idiot proof, less gamer friendly, and that’s Windows’ largest market shares, idiots and gamers.
Lmao, most games have better performance on linux so you can’t claim it’s not the best
It’s almost issue free with the exception of the publishers explicitly blocking it because it doesn’t allow them to add a rootkit to your system.
If you use this guide to mount the Windows drives you can run it and Linux side by side. It works just as good as Windows these days for 90% of games. You can add games downloaded from unofficial sites to Steam as a “Non-steam game” and it works. Installing Nvidia drivers on Mint is easier than Windows, there’s a built in utility.
There’s still the issue of overhead and such. Like I want to ditch windows forever, but Linux is just not 100% there yet with gaming. It’s very close though.
Do you know if that works for epic games and heroic launcher as well?
There’s another launcher that I’m forgetting the name of that will launch Epic and GoG games. Following that proton guide should make NTFS (windows) drives usable for anything in Linux though. I can boot games downloaded from “alternate sites” if I add them to steam as “non steam games” regardless of how the drive is mounted.
Highly recommend Pop OS! It’s been very reliable. I haven’t had anything this steady since Mac OS when I was just doing programming. I tried to go from Mac to Alienware for personal computing and it was terrible, windows blue screened almost once a week if not once every four days.
Switched to Pop OS, enabled Proton in steams preferences for gaming, and it was completely steady. Only thing that doesn’t work is the hibernate. Which isn’t a super big deal to me.
I’d actually say everything has been a better experience than windows. Lutris and pop store have a large variety of games and apps. For example lutris supports GOG and probably epic games. It feels like it’s everything I’d want without the shitty user interfaces and lack of crashes.
Which version? I got 6.4.6 a few mins ago in arch.
In seriousness: it’s in 6.4.6, 6.1.41 and a bunch of other kernel versions released yesterday.
Sorry, it’s 6.4.7. I already have your passwords, thanks
You work fast :)
Time to sit back and relax
AMD lol
Well
that’s not great
This is pretty bad but it needs local access to a server/workstation as well as pretty sophisticated knowledge/tools to exploit. Even then there’s no guarantee of getting any relevant information out of it. Anything with frequent enough logins/hashes going through the local system is probably a server someplace, and if its important you should have it physically locked away and access controlled.
Exploit is usable via JavaScript. Does not require local access.
Is there any evidence that the exploit works in a browser? A few comments on the article suggested that the Javascript engines in browsers protect against timing attacks like these.
I was hoping there would be a reply to this :(
