Tag Archives: linus

Kernel prepatch 4.17-rc1

Post Syndicated from corbet original https://lwn.net/Articles/751886/rss

Linus has released 4.17-rc1 and closed the
merge window for this release. “This does not seem to be shaping up
to be a particularly big release, and there seems to be nothing
particularly special about it. The most special thing that happened is
purely numerology: we’ve passed the six million git objects mark, and that
is reason enough to call the next kernel 5.0. Except I probably won’t,
because I don’t want to be too predictable.

[$] Kernel lockdown in 4.17?

Post Syndicated from corbet original https://lwn.net/Articles/750730/rss

The UEFI secure boot mechanism is intended to protect the system against
persistent malware threats — unpleasant bits of software attached to the
operating system or bootloader that will survive a reboot. While Linux
has supported secure boot for some time, proponents have long said that
this support is incomplete in that it is still possible for the root user
to corrupt the system in a number of ways. Patches that attempt to
close this hole have been circulating for years, but they have been
controversial at best. This story may finally come to a close, though, if
Linus Torvalds accepts the “kernel lockdown” patch series during the 4.17
merge window.

The 4.16 kernel is out

Post Syndicated from corbet original https://lwn.net/Articles/750693/rss

Linus has released the 4.16 kernel, as
expected. “We had a number of fixes and cleanups elsewhere, but none
of it made me go ‘uhhuh, better let this soak for another week’
Some of the headline changes in this release include initial support for
the Jailhouse
hypervisor, the usercopy whitelisting
hardening patches, some improvements to the deadline scheduler and, of
course, a lot of Meltdown and Spectre mitigation work.

Tech wishes for 2018

Post Syndicated from Eevee original https://eev.ee/blog/2018/02/18/tech-wishes-for-2018/

Anonymous asks, via money:

What would you like to see happen in tech in 2018?

(answer can be technical, social, political, combination, whatever)


Less of this

I’m not really qualified to speak in depth about either of these things, but let me put my foot in my mouth anyway:

The Blockchain™

Bitcoin was a neat idea. No, really! Decentralization is cool. Overhauling our terrible financial infrastructure is cool. Hash functions are cool.

Unfortunately, it seems to have devolved into mostly a get-rich-quick scheme for nerds, and by nearly any measure it’s turning into a spectacular catastrophe. Its “success” is measured in how much a bitcoin is worth in US dollars, which is pretty close to an admission from its own investors that its only value is in converting back to “real” money — all while that same “success” is making it less useful as a distinct currency.

Blah, blah, everyone already knows this.

What concerns me slightly more is the gold rush hype cycle, which is putting cryptocurrency and “blockchain” in the news and lending it all legitimacy. People have raked in millions of dollars on ICOs of novel coins I’ve never heard mentioned again. (Note: again, that value is measured in dollars.) Most likely, none of the investors will see any return whatsoever on that money. They can’t, really, unless a coin actually takes off as a currency, and that seems at odds with speculative investing since everyone either wants to hoard or ditch their coins. When the coins have no value themselves, the money can only come from other investors, and eventually the hype winds down and you run out of other investors.

I fear this will hurt a lot of people before it’s over, so I’d like for it to be over as soon as possible.

That said, the hype itself has gotten way out of hand too. First it was the obsession with “blockchain” like it’s a revolutionary technology, but hey, Git is a fucking blockchain. The novel part is the way it handles distributed consensus (which in Git is basically left for you to figure out), and that’s uniquely important to currency because you want to be pretty sure that money doesn’t get duplicated or lost when moved around.

But now we have startups trying to use blockchains for website backends and file storage and who knows what else? Why? What advantage does this have? When you say “blockchain”, I hear “single Git repository” — so when you say “email on the blockchain”, I have an aneurysm.

Bitcoin seems to have sparked imagination in large part because it’s decentralized, but I’d argue it’s actually a pretty bad example of a decentralized network, since people keep forking it. The ability to fork is a feature, sure, but the trouble here is that the Bitcoin family has no notion of federation — there is one canonical Bitcoin ledger and it has no notion of communication with any other. That’s what you want for currency, not necessarily other applications. (Bitcoin also incentivizes frivolous forking by giving the creator an initial pile of coins to keep and sell.)

And federation is much more interesting than decentralization! Federation gives us email and the web. Federation means I can set up my own instance with my own rules and still be able to meaningfully communicate with the rest of the network. Federation has some amount of tolerance for changes to the protocol, so such changes are more flexible and rely more heavily on consensus.

Federation is fantastic, and it feels like a massive tragedy that this rekindled interest in decentralization is mostly focused on peer-to-peer networks, which do little to address our current problems with centralized platforms.

And hey, you know what else is federated? Banks.


Again, the tech is cool and all, but the marketing hype is getting way out of hand.

Maybe what I really want from 2018 is less marketing?

For one, I’ve seen a huge uptick in uncritically referring to any software that creates or classifies creative work as “AI”. Can we… can we not. It’s not AI. Yes, yes, nerds, I don’t care about the hair-splitting about the nature of intelligence — you know that when we hear “AI” we think of a human-like self-aware intelligence. But we’re applying it to stuff like a weird dog generator. Or to whatever neural network a website threw into production this week.

And this is dangerously misleading — we already had massive tech companies scapegoating The Algorithm™ for the poor behavior of their software, and now we’re talking about those algorithms as though they were self-aware, untouchable, untameable, unknowable entities of pure chaos whose decisions we are arbitrarily bound to. Ancient, powerful gods who exist just outside human comprehension or law.

It’s weird to see this stuff appear in consumer products so quickly, too. It feels quick, anyway. The latest iPhone can unlock via facial recognition, right? I’m sure a lot of effort was put into ensuring that the same person’s face would always be recognized… but how confident are we that other faces won’t be recognized? I admit I don’t follow all this super closely, so I may be imagining a non-problem, but I do know that humans are remarkably bad at checking for negative cases.

Hell, take the recurring problem of major platforms like Twitter and YouTube classifying anything mentioning “bisexual” as pornographic — because the word is also used as a porn genre, and someone threw a list of porn terms into a filter without thinking too hard about it. That’s just a word list, a fairly simple thing that any human can review; but suddenly we’re confident in opaque networks of inferred details?

I don’t know. “Traditional” classification and generation are much more comforting, since they’re a set of fairly abstract rules that can be examined and followed. Machine learning, as I understand it, is less about rules and much more about pattern-matching; it’s built out of the fingerprints of the stuff it’s trained on. Surely that’s just begging for tons of edge cases. They’re practically made of edge cases.

I’m reminded of a point I saw made a few days ago on Twitter, something I’d never thought about but should have. TurnItIn is a service for universities that checks whether students’ papers match any others, in order to detect cheating. But this is a paid service, one that fundamentally hinges on its corpus: a large collection of existing student papers. So students pay money to attend school, where they’re required to let their work be given to a third-party company, which then profits off of it? What kind of a goofy business model is this?

And my thoughts turn to machine learning, which is fundamentally different from an algorithm you can simply copy from a paper, because it’s all about the training data. And to get good results, you need a lot of training data. Where is that all coming from? How many for-profit companies are setting a neural network loose on the web — on millions of people’s work — and then turning around and selling the result as a product?

This is really a question of how intellectual property works in the internet era, and it continues our proud decades-long tradition of just kinda doing whatever we want without thinking about it too much. Nothing if not consistent.

More of this

A bit tougher, since computers are pretty alright now and everything continues to chug along. Maybe we should just quit while we’re ahead. There’s some real pie-in-the-sky stuff that would be nice, but it certainly won’t happen within a year, and may never happen except in some horrific Algorithmic™ form designed by people that don’t know anything about the problem space and only works 60% of the time but is treated as though it were bulletproof.


The giants are getting more giant. Maybe too giant? Granted, it could be much worse than Google and Amazon — it could be Apple!

Amazon has its own delivery service and brick-and-mortar stores now, as well as providing the plumbing for vast amounts of the web. They’re not doing anything particularly outrageous, but they kind of loom.

Ad company Google just put ad blocking in its majority-share browser — albeit for the ambiguously-noble goal of only blocking obnoxious ads so that people will be less inclined to install a blanket ad blocker.

Twitter is kind of a nightmare but no one wants to leave. I keep trying to use Mastodon as well, but I always forget about it after a day, whoops.

Facebook sounds like a total nightmare but no one wants to leave that either, because normies don’t use anything else, which is itself direly concerning.

IRC is rapidly bleeding mindshare to Slack and Discord, both of which are far better at the things IRC sadly never tried to do and absolutely terrible at the exact things IRC excels at.

The problem is the same as ever: there’s no incentive to interoperate. There’s no fundamental technical reason why Twitter and Tumblr and MySpace and Facebook can’t intermingle their posts; they just don’t, because why would they bother? It’s extra work that makes it easier for people to not use your ecosystem.

I don’t know what can be done about that, except that hope for a really big player to decide to play nice out of the kindness of their heart. The really big federated success stories — say, the web — mostly won out because they came along first. At this point, how does a federated social network take over? I don’t know.

Social progress

I… don’t really have a solid grasp on what’s happening in tech socially at the moment. I’ve drifted a bit away from the industry part, which is where that all tends to come up. I have the vague sense that things are improving, but that might just be because the Rust community is the one I hear the most about, and it puts a lot of effort into being inclusive and welcoming.

So… more projects should be like Rust? Do whatever Rust is doing? And not so much what Linus is doing.

Open source funding

I haven’t heard this brought up much lately, but it would still be nice to see. The Bay Area runs on open source and is raking in zillions of dollars on its back; pump some of that cash back into the ecosystem, somehow.

I’ve seen a couple open source projects on Patreon, which is fantastic, but feels like a very small solution given how much money is flowing through the commercial tech industry.

Ad blocking

Nice. Fuck ads.

One might wonder where the money to host a website comes from, then? I don’t know. Maybe we should loop this in with the above thing and find a more informal way to pay people for the stuff they make when we find it useful, without the financial and cognitive overhead of A Transaction or Giving Someone My Damn Credit Card Number. You know, something like Bitco— ah, fuck.

Year of the Linux Desktop

I don’t know. What are we working on at the moment? Wayland? Do Wayland, I guess. Oh, and hi-DPI, which I hear sucks. And please fix my sound drivers so PulseAudio stops blaming them when it fucks up.

Kernel prepatch 4.16-rc1

Post Syndicated from corbet original https://lwn.net/Articles/747068/rss

Linus has released 4.16-rc1 and closed the
merge window for this development cycle. “I don’t want to jinx
anything, but things certainly look a lot better than with 4.15. We have no
(known) nasty surprises pending, and there were no huge issues during the
merge window. Fingers crossed that this stays fairly calm and sane.

The 4.15 kernel is out

Post Syndicated from corbet original https://lwn.net/Articles/744875/rss

Linus has released the 4.15 kernel.
After a release cycle that was unusual in so many (bad) ways, this
last week was really pleasant. Quiet and small, and no last-minute
panics, just small fixes for various issues. I never got a feeling
that I’d need to extend things by yet another week, and 4.15 looks
fine to me.

Some of the more significant features in this release include:
the long-awaited CPU controller for the
version-2 control-group interface,
significant live-patching improvements,
initial support for the RISC-V architecture,
support for AMD’s secure encrypted virtualization feature, and
the MAP_SYNC mechanism for working
with nonvolatile memory.
This release also, of course, includes mitigations for the Meltdown and Spectre variant-2
though, as Linus points out in the announcement, the
work of dealing with these issues is not yet done.

On that Spectre mitigations discussion

Post Syndicated from corbet original https://lwn.net/Articles/745111/rss

By now, almost everybody has probably seen the press coverage of Linus Torvalds’s remarks about one of the
patches addressing Spectre variant 2. Less noted, but much more
informative, is David Woodhouse’s response
on why those patches are the way they are. “That’s why my initial
idea, as implemented in this RFC patchset, was to stick with IBRS on
Skylake, and use retpoline everywhere else. I’ll give you ‘garbage
patches’, but they weren’t being ‘just mindlessly sent around’. If we’re
going to drop IBRS support and accept the caveats, then let’s do it as a
conscious decision having seen what it would look like, not just drop it
quietly because poor Davey is too scared that Linus might shout at him

No 4.15 final release today

Post Syndicated from corbet original https://lwn.net/Articles/744907/rss

As might have been expected from watching the commit stream, the 4.15
kernel is not ready for release, so we’ll get 4.15-rc9 instead.
Linus said: “I really really wanted to just release 4.15 today, but things haven’t
calmed down enough for me to feel comfy about it, and Davem tells me
he still has some networking fixes pending. Laura Abbott found and
fixed a very subtle boot bug introduced this development cycle only
yesterday, and it just didn’t feel right to say that we’re done.

Security updates for Monday

Post Syndicated from ris original https://lwn.net/Articles/744398/rss

Security updates have been issued by Arch Linux (qtpass), Debian (libkohana2-php, libxml2, transmission, and xmltooling), Fedora (kernel and qpid-cpp), Gentoo (PolarSSL and xen), Mageia (flash-player-plugin, irssi, kernel, kernel-linus, kernel-tmb, libvorbis, microcode, nvidia-current, php & libgd, poppler, webkit2, and wireshark), openSUSE (gifsicle, glibc, GraphicsMagick, gwenhywfar, ImageMagick, libetpan, mariadb, pngcrush, postgresql94, rsync, tiff, and wireshark), and Oracle (kernel).

Security updates for Monday

Post Syndicated from ris original https://lwn.net/Articles/743575/rss

Security updates have been issued by Arch Linux (linux-hardened, linux-lts, linux-zen, and mongodb), Debian (gdk-pixbuf, gifsicle, graphicsmagick, kernel, and poppler), Fedora (dracut, electron-cash, and firefox), Gentoo (backintime, binutils, chromium, emacs, libXcursor, miniupnpc, openssh, optipng, and webkit-gtk), Mageia (kernel, kernel-linus, kernel-tmb, openafs, and python-mistune), openSUSE (clamav-database, ImageMagick, kernel-firmware, nodejs4, and qemu), Red Hat (linux-firmware, ovirt-guest-agent-docker, qemu-kvm-rhev, redhat-virtualization-host, rhev-hypervisor7, rhvm-appliance, thunderbird, and vdsm), Scientific Linux (thunderbird), SUSE (kernel and qemu), and Ubuntu (firefox and poppler).

Some notes on Meltdown/Spectre

Post Syndicated from Robert Graham original http://blog.erratasec.com/2018/01/some-notes-on-meltdownspectre.html

I thought I’d write up some notes.

You don’t have to worry if you patch. If you download the latest update from Microsoft, Apple, or Linux, then the problem is fixed for you and you don’t have to worry. If you aren’t up to date, then there’s a lot of other nasties out there you should probably also be worrying about. I mention this because while this bug is big in the news, it’s probably not news the average consumer needs to concern themselves with.

This will force a redesign of CPUs and operating systems. While not a big news item for consumers, it’s huge in the geek world. We’ll need to redesign operating systems and how CPUs are made.

Don’t worry about the performance hit. Some, especially avid gamers, are concerned about the claims of “30%” performance reduction when applying the patch. That’s only in some rare cases, so you shouldn’t worry too much about it. As far as I can tell, 3D games aren’t likely to see less than 1% performance degradation. If you imagine your game is suddenly slower after the patch, then something else broke it.

This wasn’t foreseeable. A common cliche is that such bugs happen because people don’t take security seriously, or that they are taking “shortcuts”. That’s not the case here. Speculative execution and timing issues with caches are inherent issues with CPU hardware. “Fixing” this would make CPUs run ten times slower. Thus, while we can tweek hardware going forward, the larger change will be in software.

There’s no good way to disclose this. The cybersecurity industry has a process for coordinating the release of such bugs, which appears to have broken down. In truth, it didn’t. Once Linus announced a security patch that would degrade performance of the Linux kernel, we knew the coming bug was going to be Big. Looking at the Linux patch, tracking backwards to the bug was only a matter of time. Hence, the release of this information was a bit sooner than some wanted. This is to be expected, and is nothing to be upset about.

It helps to have a name. Many are offended by the crassness of naming vulnerabilities and giving them logos. On the other hand, we are going to be talking about these bugs for the next decade. Having a recognizable name, rather than a hard-to-remember number, is useful.

Should I stop buying Intel? Intel has the worst of the bugs here. On the other hand, ARM and AMD alternatives have their own problems. Many want to deploy ARM servers in their data centers, but these are likely to expose bugs you don’t see on x86 servers. The software fix, “page table isolation”, seems to work, so there might not be anything to worry about. On the other hand, holding up purchases because of “fear” of this bug is a good way to squeeze price reductions out of your vendor. Conversely, later generation CPUs, “Haswell” and even “Skylake” seem to have the least performance degradation, so it might be time to upgrade older servers to newer processors.

Intel misleads. Intel has a press release that implies they are not impacted any worse than others. This is wrong: the “Meltdown” issue appears to apply only to Intel CPUs. I don’t like such marketing crap, so I mention it.

Statements from companies:

Security updates for Friday

Post Syndicated from jake original https://lwn.net/Articles/742134/rss

Security updates have been issued by Debian (bouncycastle, enigmail, and sensible-utils), Fedora (kernel), Mageia (dhcp, flash-player-plugin, glibc, graphicsmagick, java-1.8.0-openjdk, kernel, kernel-linus, kernel-tmb, mariadb, pcre, rootcerts, rsync, shadow-utils, and xrdp), and SUSE (java-1_8_0-ibm and kernel).

Why Linus is right (as usual)

Post Syndicated from Robert Graham original http://blog.erratasec.com/2017/11/why-linus-is-right-as-usual.html

People are debating this email from Linus Torvalds (maintainer of the Linux kernel). It has strong language, like:

Some security people have scoffed at me when I say that security
problems are primarily “just bugs”.
Those security people are f*cking morons.
Because honestly, the kind of security person who doesn’t accept that
security problems are primarily just bugs, I don’t want to work with.

I thought I’d explain why Linus is right.
Linus has an unwritten manifesto of how the Linux kernel should be maintained. It’s not written down in one place, instead we are supposed to reverse engineer it from his scathing emails, where he calls people morons for not understanding it. This is one such scathing email. The rules he’s expressing here are:
  • Large changes to the kernel should happen in small iterative steps, each one thoroughly debugged.
  • Minor security concerns aren’t major emergencies; they don’t allow bypassing the rules more than any other bug/feature.
Last year, some security “hardening” code was added to the kernel to prevent a class of buffer-overflow/out-of-bounds issues. This code didn’t address any particular 0day vulnerability, but was designed to prevent a class of future potential exploits from being exploited. This is reasonable.
This code had bugs, but that’s no sin. All code has bugs.
The sin, from Linus’s point of view, is that when an overflow/out-of-bounds access was detected, the code would kill the user-mode process or kernel. Linus thinks it should have only generated warnings, and let the offending code continue to run.
Of course, that would in theory make the change of little benefit, because it would no longer prevent 0days from being exploited.
But warnings would only be temporary, the first step. There’s likely to be be bugs in the large code change, and it would probably uncover bugs in other code. While bounds-checking is a security issue, its first implementation will always find existing code having latent bounds bugs. Or, it’ll have “false-positives” triggering on things that aren’t actually the flaws its looking for. Killing things made these bugs worse, causing catastrophic failures in the latest kernel that didn’t exist before. Warnings, however, would have equally highlighted the bugs, but without causing catastrophic failures. My car runs multiple copies of Linux — such catastrophic failures would risk my life.
Only after a year, when the bugs have been fixed, would the default behavior of the code be changed to kill buggy code, thus preventing exploitation.
In other words, large changes to the kernel should happen in small, manageable steps. This hardening hasn’t existed for 25 years of the Linux kernel, so there’s no emergency requiring it be added immediately rather than conservatively, no reason to bypass Linus’s development processes. There’s no reason it couldn’t have been warnings for a year while working out problems, followed by killing buggy code later.
Linus was correct here. No vuln has appeared in the last year that this code would’ve stopped, so the fact that it killed processes/kernels rather than generated warnings was unnecessary. Conversely, because it killed things, bugs in the kernel code were costly, and required emergency patches.
Despite his unreasonable tone, Linus is a hugely reasonable person. He’s not trying to stop changes to the kernel. He’s not trying to stop security improvements. He’s not even trying to stop processes from getting killed That’s not why people are moronic. Instead, they are moronic for not understanding that large changes need to made conservatively, and security issues are no more important than any other feature/bug.

Update: Also, since most security people aren’t developers, they are also a bit clueless how things actually work. Bounds-checking, which they define as purely a security feature to stop buffer-overflows is actually overwhelmingly a debugging feature. When you turn on bounds-checking for the first time, it’ll trigger on a lot of latent bugs in the code — things that never caused a problem in the past (like reading past ends of buffers) but cause trouble now. Developers know this, security “experts” tend not to. These kernel changes were made by security people who failed to understand this, who failed to realize that their changes would uncover lots of bugs in existing code, and that killing buggy code was hugely inappropriate.

Update: Another flaw developers are intimately familiar with is how “hardening” code can cause false-positives, triggering on non-buggy code. A good example is where the BIND9 code crashed on an improper assert(). This hardening code designed to prevent exploitation made things worse by triggering on valid input/code.

Update: No, it’s probably not okay to call people “morons” as Linus does. They may be wrong, but they usually are reasonable people. On the other hand, security people tend to be sanctimonious bastards with rigid thinking, so after he has dealt with that minority, I can see why Linus treats all security people that way.

[$] 4.15 Merge window part 1

Post Syndicated from corbet original https://lwn.net/Articles/739341/rss

When he released 4.14, Linus Torvalds
warned that the 4.15 merge window might be shorter than usual due to the US
Thanksgiving holiday. Subsystem maintainers would appear to have heard
him; as of this writing, over 8,800 non-merge changesets have been pulled
into the mainline since the opening of the 4.15 merge window. Read on for
a summary of the most interesting changes found in that first set of

The 4.14 kernel has been released

Post Syndicated from corbet original https://lwn.net/Articles/738810/rss

The 4.14 kernel has been released after a
ten-week development cycle.

Some of the most prominent features in this release include
the ORC unwinder for more reliable
tracebacks and live patching,
the long-awaited thread mode for control
support for AMD’s secure memory
five-level page table support,
a new zero-copy networking feature,
the heterogeneous memory management
and more.
In the end, nearly 13,500 changesets were merged for 4.14, which is slated
to be the next long-term-support kernel.

For the maintainers out there, it’s worth noting Linus’s warning that the
4.15 merge window might be rather shorter than usual due to the US
Thanksgiving Holiday.