8 ms·

Linux kernel security work

189 points by chmaynard 9mo ago

JCattheATM 9mo ago
Their view that security bugs are just normal bugs remains very immature and damaging. It it somewhat mitigated by Linux having so many eyes on it and so many developers, but a lot of problems in the past could have bee avoided if they adopted the stance the rest of the industry recognizes as correct.
- tptacek 9mo ago
  From their perspective, on their project, with the constraints they operate under, bugs are just bugs. You're free to operationalize some other taxonomy of bugs in your organization; I certainly wouldn't run with "bugs are just bugs" in mine (security bugs are distinctive in that they're paired implicitly with adversaries). To complicate matters further, it's not as if you could rely on any more "sophisticated" taxonomy from the Linux kernel team, because they're not the originators of most Linux kernel security findings, and not all the actual originators are benevolent.
  - rwmj 9mo ago
    For sure, but you don't need to file CVEs for every regular bug.
    - Skunkleton 9mo ago
      In the context of the kernel, it’s hard to say when that’s true. It’s very easy to fix some bug that resulted in a kernel crash without considering that it could possibly be part of some complex exploit chain. Basically any bug could be considered a security bug.
      - SSLy 9mo ago
        plainly, crash = DoS = security issue = CVE. QED.
        deleted 9mo ago
        [deleted]
        michaelt 9mo ago
        BRB, raising a CVE complaining the OOM killer exists.
        pamcake 9mo ago
        Memory leaks are usually (accurately) treated as DoS. OoM killer is a mitigation to contain them and not DoS the entire OS.
        worthless-trash 9mo ago
        I could be wrong. But operation by design isn't considered a bug.
        samus 9mo ago
        It is if some other condition is violated that is more important. Then the design might have to be reconsidered.
        suspended_state 9mo ago
        If it is faulty, then it's not a bug, it's a flaw.
        lfllfkddl 9mo ago
        It is possible to design a security vulnerability.
        worthless-trash 9mo ago
        Oh, now that is an exciting area.
  - JCattheATM 9mo ago
    > From their perspective, on their project, with the constraints they operate under, bugs are just bugs. That's a pretty poor justification. Their perspective is wrong, and their constraints don't prevent them from treating security bugs differently as they should.
    - ada0000 9mo ago
      > almost any bugfix at the level of an operating system kernel can be a “security issue” given the issues involved (memory leaks, denial of service, information leaks, etc.) On the level of the Linux kernel, this does seem convincing. There is no shared user space on Linux where you know how each component will react/recover in the face of unexpected kernel behaviour, and no SKUs targeting specific use cases in which e.g. a denial of service might be a worse issue than on desktop. I guess CVEs provide some of this classification, but they seem to cause drama amongst kernel people.
    - samus 9mo ago
      You have a pretty strongly worded stance, but you don't provide an argument for it. May I suggest you detail why exactly you think their perspective is wrong, apart from "a lot of problems in the past could have been avoided"?
      - JCattheATM 9mo ago
        My view here isn't uncommon, even if it's a minority view. I've noticed a lot of people tend to just defend and adopt the stances of projects they like or use without necessarily thinking things through, and I assume that's at least partly the case here. There's been a lot of criticism written on the kernel devs stance over the last, what, 20 years? One obvious problem is that without giving security bugs, i.e. vulnerabilities priority, systems stay vulnerable until the bug gets patched at whatever place in the queue it happens to be at.
- beanjuiceII 9mo ago
  did you read it? because that's not their view at all
- firesteelrain 9mo ago
  “A bug is a bug” is about communication and prioritization, not ignoring security. Greg’s post spells that out pretty clearly.
  - JCattheATM 9mo ago
    Yes, that's what I was criticizing....
- akerl_ 9mo ago
  This feels almost too obvious to be worth saying, but “the rest of the industry” does not in fact have a uniform shared stance on this.
- jacobsenscott 9mo ago
  Classifying bugs as security bugs is just theater - and any company or organization that tries to classify bugs that way is immature and hasn't put any thought into it. First of all "security" is undefined. Second, nearly every bug can be be exploited in a malicious way, but that way is usually not easy to find. So should every bug be classified as a security bug? Or should only bugs where a person can think of a way on the spot during triage to exploit that bug as a security bug? In that case only a small subset of your "security" bugs are classified as such. It is meaningless in all cases.
  - JCattheATM 9mo ago
    > First of all "security" is undefined. Nonsense.
  - therealrootuser 9mo ago
    > nearly every bug can be be exploited in a malicious way This is a bit contextually dependent. "This widget is the wrong color" is probably not a security issue in most cases, unless the widget happens to be a traffic signal, in which case it is a major safety concern. Even the line between "this is a bug" and "this is just a missing, incomplete, or poorly thought out feature" can get a bit blurry. At a certain point, many engineers get frustrated trying to pick apart the difference between all these ways of classifying the code they are writing and just want to get on with making the system work better.
  - ykonstant 9mo ago
    > "security" Security is not a dirty word, Blackadder.
  - staticassertion 9mo ago
    > First of all "security" is undefined. No it isn't. Security boundaries exist and are explicit. It isn't undefined at all. Going from user X to user Y without permission to do so is an explicit vulnerability. The kernel has permissions boundaries. They are explicit. It is defined. > Second, nearly every bug can be be exploited in a malicious way, No they can't.
- themafia 9mo ago
  > a lot of problems in the past could have bee avoided Such as?
- schmuckonwheels 9mo ago
  Linus has been very clear on avoiding the opposite, which is the OpenBSD situation: they obsess about security so much that nothing else matters to them, which is how you end up with a mature 30 year old OS that still has a dogshit unreliable filesystem in 2026. To paraphrase LT, security bugs are important, but so are all the other bugs.
  - JCattheATM 9mo ago
    OpenBSD doesn't really stress about security so much as they made that their identity and marketing campaign - their OS is lacking too many basic capabilities a security focused OS should have. > To paraphrase LT, security bugs are important, but so are all the other bugs. Right, this is wrong, and that's the problem. Security bugs as a class are always going to be more important than certain other classes of bugs.
    - cedws 9mo ago
      And their ‘no remote holes’ is true for a base install with no packages, not necessarily a full system. I think the OpenBSD approach of secure coding is outdated. The goal should have always been to take human error out of the equation as much as possible. Rust and other modern memory safe languages move things in that direction, you don’t need ultra strict coding standards and a bible of compiler flags.
      - JCattheATM 9mo ago
        > I think the OpenBSD approach of secure coding is outdated. I don't think it's outdated it's a core part of the puzzle. The problem with their approach is they rely on it 100%, and have not enough in place (and yes, I'm aware of all the mitigations they do have) to protect against bugs they miss. This is a lot less true now than it was 15 - 20 years ago, but it's still not great IMO.
    - 6r17 9mo ago
      I have to disagree it's worst than you think ; open-bsd has so many mitigation in place that your computer will probably run 50% slower than a traditional OS. In reality you do not want to be playing 100% safety everywhere because this is simply expensive. You might prefer to create an isolated network on which you can set up un-mitigated servers - those will be able to run at 100% capacity. This can be looked upon when compiling the linux kernel, the mitigation options are rather numerous - and you'll have to also pick a sleep time ; what i'm saying is - currently linux only allows you to tune a machine to a specific requirement - it's not a spaceship on which you can change the sleep time frequency; dynamically shutdown mitigation ; and imagine that you are performing - In the same spirit, if you are holding keys on anything else than open-bsd ; I hope for you that you have properly looked up what you were installing.
- redleader55 9mo ago
  The rest of the industry relies on following a CVE list and ticking off vulnerabilities as a way to ensure "owners" are correctly assigned risk and sign it off - because there is nothing else that "owners" could do. The whole security through CVE is broken and is designed to be useful to create large "security organizations" that have the single purpose of annoying everyone with reports without solving any issues.
- deleted 9mo ago
  [deleted]
DebugDruid 9mo ago
Sometimes I dream about a 100% secure OS. Maybe formal verification is the key, or Rust, I don’t know. But I would love to know that I can't be hacked.
- jeffbee 9mo ago
  The problem is that for the overwhelming majority of use cases the isolation features that are violated by security bugs are not being used for real isolation, but for manageability and convenience. Virtualization, physical host segregation, etc are used to achieve greater isolation. People don't necessarily care about these flaws because they aren't actually exposed to the worst case preconditions. So the amount of contributor attention you could get behind a "100% secure OS" might not be as large as you are hoping. Anyway if you want to work on such things there are various OS development efforts floating around.
  - nine_k 9mo ago
    Isolation is one thing, correctness is another. You may have architecturally perfect, hardware-assisted isolation, but triggering a bug would breach it. This is how a typical break out of a VM, or a container, or a privilege escalation, happens. There is a difference between a provably secure-by-design system, and a formally proven secure implementation, like Sel4.
  - ameliaquining 9mo ago
    Obligatory https://xkcd.com/2044/ https://xkcd.com/2044/.
- themafia 9mo ago
  > But I would love to know that I can't be hacked. Cool. So social engineering it is. You are your own worst enemy anyways.
  - staticassertion 9mo ago
    A world in which the only way to get hacked is to be tricked would be an insane improvement over today. There are a lot of ways to solve social engineering issue with tech solutions too - FIDO2 is one example, as would be app isolation, etc.
ryanisnan 9mo ago
[flagged]
- cogman10 9mo ago
  Why? What benefit would https provide over http when visiting a pure information (and I'm guessing statically generated) website?
  - fordsmith 9mo ago
    If you are on a public network without using a VPN you open yourself up to MITM to inject something malicious
    - cogman10 9mo ago
      Sure, but that's ultimately a pretty unlikely attack vector. An attacker still needs to exploit some unknown vulnerability of your web browser in order to get something malicious going. I basically expect that sort of attack to only be pulled off by a state actor or by a black hat convention for the lolz.
      - nine_k 9mo ago
        ISPs used to inject ads into HTTP-served pages as recently as 10 years ago, I personally remember that. Not only tiny ISPs. I'm not alone: https://superuser.com/questions/902635/isp-is-inserting-ads-into-web-pages https://superuser.com/questions/902635/isp-is-inserting-ads-... Ads injection is a relatively benign kind of tampering. It could be much more creative and sinister.
      - deleted 9mo ago
        [deleted]
  - bqmjjx0kac 9mo ago
    Confidentiality, integrity, and authenticity :)
miduil 9mo ago
> If you are forced to use encryption to report security problems, please reconsider this policy as it feels counterproductive (UK government, this means you…) LOL
vlovich123 9mo ago
I think the most practical reason not to flag which bugs are security bugs is to avoid helping blackhat hackers by painting a giant neon sign and that should be more than enough. I think all the other explanations are just double-think. Why? If "bugs are just bugs" is really a true sentiment, why is there a separate disclosure process for security bugs? What does it even mean to classify a bug as a security bug during reporting if it's no different than any other bug report? Why are fixes developed in secret & potential embargoes sometimes invoked? I guess some bugs are more equal than others?
- fguerraz 9mo ago
  As mentioned in the article, every bug is potentially a security problem to someone. If you know that something is a security issue to your organization, you definitely don't want to paint a target on your back by reporting the bug publicly with an email address <your_name>@<your_org>.com. In the end, it is really actually quite rare (given the size of the code base and the popularity of linux) that a bug has a very wide security impact. The vast majority of security issues don't affect organizations that are serious about security (yes really, SELinux eliminates or seriously reduces the impact of the vast majority of security bugs).
  - vlovich123 9mo ago
    The problem with that argument is that the reports don’t necessarily come from the organization for whom it’s an issue. Security researchers unaffiliated not impacted by any such issue still report it this way (eg Project Zero reporting issues that don’t impact Google at all). Also Android uses SELinux and still has lots of kernel exploits. Believing SELinux solves the vast majority of security issues is fallacious, especially since it’s primarily about securing userspace, not the kernel itself .
    - suspended_state 9mo ago
      > The problem with that argument is that the reports don’t necessarily come from the organization for whom it’s an issue. You can already say that for the majority of the bugs being fixed, and I think that's one of the points: tagging certain bugs as exploitable make it seem like the others aren't. More generally, someone's minor issue might be a major one for someone else, and not just in security. It could be anything the user cares about, data, hardware, energy, time. Perhaps the real problem is that security is just a view on the bigger picture. Security is important, I'm not saying the opposite, but if it's only an aspect of development, why focus on it in the development logs? Shouldn't it be instead discussed on its own, in separate documents, mailing lists, etc by those who are primarily concerned by it?
badgersnake 9mo ago
And then all our customers will demand fixes for them in our docker images, because they’re that smart. There must be a way to ship a docker image without a kernel, since it doesn’t get used for anything anyway.
- derkades 9mo ago
  Huh, how do you unintentionally ship a Linux kernel in a container image? The common base images definitely don't contain the kernel.
  - staticassertion 9mo ago
    The only thing I can imagine is that they've somehow managed to rely on kernel headers in their image? idk
    - deleted 9mo ago
      [deleted]
- shepherdjerred 9mo ago
  https://github.com/wolfi-dev https://github.com/wolfi-dev
coppsilgold 9mo ago
Recently, things have been advancing which may finally allow a seamless virtualization experience on the Linux desktop (and match QubesOS in some security aspects). GPU drivers supporting native contexts with Mesa support. Wayland sharing between guest and host. It used to be somewhat sloppy (involved protocol parsing; sommilier & wayland-proxy-virtwl) but recently someone undertook a project to do it properly that may soon bear fruit: https://codeberg.org/drakulix/wl-cross-domain-proxy https://codeberg.org/drakulix/wl-cross-domain-proxy A VMM to utilize these features: https://github.com/AsahiLinux/muvm https://github.com/AsahiLinux/muvm And a solution which ties these things together: https://git.clan.lol/clan/munix https://git.clan.lol/clan/munix
- conradev 9mo ago
  This is really cool! I wonder if it would be possible to live-migrate apps from one machine running munix to another. You could pause, transfer, and resume the virtual machine.
_zagj 9mo ago
Meanwhile it's 2026 and Greg's own website still doesn't support TLS.
- juliangmp 9mo ago
  Honestly, until encrypted client hello has widespread support, why bother? I mean I did it for fun the first time and now with caddy its not a lot of effort. But for a personal blog, a completely static site, what benefit do you get from the encryption? Anyone monitoring the traffic will see the domain in clear text anyway. And they'd see the destination IP, which I imagine in this case being one server that has exactly one domain pointed at it.
  - swinglock 9mo ago
    Men in the middle including predatory ISPs can not only spy but also enrich. Injecting JavaScript and embedding ads is the best case scenario. You don't want that. In addition even without bad actors TLS will prevent random corruption due to flaky infrastructure from breaking the page and even caching those broken assets, preventing a reload from fixing it. TCP/IP alone doesn't sufficiently prevent this.
    - psnehanshu 9mo ago
      TCP ensures what gets sent on one side gets received on the other side. TLS just encrypts the data. So even without TLS, random corruptions won't happen unless someone does MITM attack.
      - swinglock 9mo ago
        No it does not. I've had this happen in legacy systems myself. The checksums of TCP/IP are weak and will let random errors through to L7 if there are enough of them. It's not even CRC and you must bring your own verification if it's critical for your application that the data is correct. TLS does that and more, protecting not only against random corruption but also active attackers. The checks you get for free are to be seen only as an optimization, letting most but not all errors be discarded quick and easy. Just use TLS.
tuananh 9mo ago
this is why redhat is still relevant in 2025. there's always a need for this kind of work.
- staticassertion 9mo ago
  I think you could make a stronger case for the opposite. How does Redhat know which commits to cherry when upstream explicitly won't tell you which are relevant to security?
  - invokestatic 9mo ago
    Because Red Hat pays the salaries of dozens (hundreds?) of kernel maintainers all over different subsystems. So they’re subject matter experts, and know exactly which ones are relevant to Red Hat.
    - thrwwy81faa457 9mo ago
      This is the right answer. Source: 10+y long (past) tenure at RH in a team adjacent to the kernel team. EDIT: also because companies like RH tend to know, and are happy to know, the details of their customers' deployments. Compare the article: > Always remember, kernel developers: > - do not know your use case. > - do not know what code you use. > - do not want to know any of this.
      - staticassertion 9mo ago
        https://bugzilla.redhat.com/show_bug.cgi?id=1708775 https://bugzilla.redhat.com/show_bug.cgi?id=1708775 https://www.openwall.com/lists/oss-security/2020/06/23/2 https://www.openwall.com/lists/oss-security/2020/06/23/2 Even RHEL misses things that don't get announced. This is a big issue for LTS kernels and downstreams, although RHEL does a much better job than most due to the nature of the company/ products. I don't have tons of examples off hand but Spender and Project Zero have a number of examples like this (not necessarily for RHEL! Just in general where lack of CVE led to downstreams not being patched). https://googleprojectzero.github.io/0days-in-the-wild/0day-RCAs/2021/CVE-2021-1048.html https://googleprojectzero.github.io/0days-in-the-wild/0day-R... Who is helped by this, for example? https://x.com/grsecurity/status/1486795432202276864 https://x.com/grsecurity/status/1486795432202276864 > Always remember, kernel developers: > - do not know your use case. > - do not know what code you use. > - do not want to know any of this. I just found this part so odd. You don't need to know how users are deploying code to know that a type confusion in an unprivileged system call that leads to full control over the kernel is a vulnerability. If someone has a very strange deployment where that isn't the case, okay, they can choose not to patch. It's odd for every distro to have to think "is this patch for a vulnerability?" with no insight from upstream on the matter. Thankfully, researchers can go out of their way to get a CVE assigned.
tuananh 9mo ago
if they really think that, they should have remove their CNA, no?
- theamk 9mo ago
  Nah, "removing CNA" = "let any security researcher decide what kernel vulnerability is" And unfortunately, there are plenty of security researchers who are only interested in personal CVE counts, and will try to assign highest priority to a mostly harmless bug.
  - tuananh 9mo ago
    but keeping the CNA and decide, "nah, i wont number it" instead?
    - theamk 9mo ago
      They do number it.. in fact once they become CNA in 2024, the amount of kernel CVE's has increased almost 10x (see [0]) They just stopped assigning priorities/impact scores to them, because "A simple bugfix for a minor thing for one user could be a major system vulnerability fix for a different user, all depending on how Linux is being used" (For an example of why having severity rating on CVE is a bad idea, see Redhat's treatment of CVE-2025-68343[1] - they gave "high", score 7. Many security teams in large corps would require a quick patch/kernel upgrade. And yes, this is a null-pointer dereference in a single USB device driver. Even if this is exploitable (which I am not sure about), this driver is _never_ going to be loaded into any our cloud machines, so most of our infra is not affected). [0] https://www.cvedetails.com/product/47/Linux-Linux-Kernel.html?vendor_id=33 https://www.cvedetails.com/product/47/Linux-Linux-Kernel.htm... [1] https://access.redhat.com/security/cve/cve-2025-68343 https://access.redhat.com/security/cve/cve-2025-68343
staticassertion 9mo ago
"A bug is a bug" lol. There's a massive difference between "DoS requiring root" and "I can own you from an unprivileged user with one system call". You can say "but that DoS could have been a privesc! We don't know!" but no one is arguing otherwise? The point is that we do know the impact of some bugs is strictly a superset of other bugs, and when those bugs give control or allow a violation of a defined security boundary, those are security bugs. This has all been explained to Greg for decades, nothing will change so it's just best to accept the state - I'm glad it's been documented clearly. Know this - your kernel is not patched unless you run the absolute latest version. CVEs are discouraged, vuln fixes are obfuscated, and you should operate under that knowledge. Attackers know how to watch the commit log for these hidden fixes btw, it's not that hard. edit: Years later and I'm still rate limited so I can't reply. @dang can this be fixed? I was rate limited for posting about Go like... years ago. To the person who replies to me: > This is correct for a lot of different software, probably most of it. Why is this a point that needs to be made? That's not true at all. You can know if you're patched for any software that discloses vulnerabilities by checking if your release is up to date. That is not true of Linux, by policy, hence this entire post by Greg and the talks he's given about suggesting you run rolling releases. Sorry but it's too annoying to reply further with this rate limiting, so I'll be unable to defend my points.
- tamirzb 9mo ago
  > Know this - your kernel is not patched unless you run the absolute latest version. This is correct for a lot of different software, probably most of it. Why is this a point that needs to be made?
  - thrwwy81faa457 9mo ago
    (Parent has already replied by editing their original comment, but I'll tack on a bit more info, from my perspective.) The reason this has to be emphasized is that all new code runs the risk of regressions, and in a production environment, you hate regressions. Therefore, not only do you not want new features, but you also don't want irrelevant bug fixes. Bug fixes, even security fixes, are not magically free of independent regressions. Therefore a valid incentive exists to minimize backports to production environments. And such a balancing act depends on the careful investigation of the impact of known bugs, one by one. From the fine blog post: > For those that are always worried “what if a bugfix causes problems”, they should remember that a fix for a known bug is better than the potential of a fix causing a future problem as future problems, when found, will be fixed then. A whole lot of users can disagree with this. For good, practical reasons. The expected damage of a known bug may be estimated, while an unknown regression brought in by the fix for the known bug may cause way worse damage.
bschmidt25011 9mo ago
[dead]

189 points by chmaynard 9mo ago

Their view that security bugs are just normal bugs remains very immature and damaging. It it somewhat mitigated by Linux having so many eyes on it and so many developers, but a lot of problems in the past could have bee avoided if they adopted the stance the rest of the industry recognizes as correct.

tptacek 9mo ago
From their perspective, on their project, with the constraints they operate under, bugs are just bugs. You're free to operationalize some other taxonomy of bugs in your organization; I certainly wouldn't run with "bugs are just bugs" in mine (security bugs are distinctive in that they're paired implicitly with adversaries). To complicate matters further, it's not as if you could rely on any more "sophisticated" taxonomy from the Linux kernel team, because they're not the originators of most Linux kernel security findings, and not all the actual originators are benevolent.
- rwmj 9mo ago
  For sure, but you don't need to file CVEs for every regular bug.
  - Skunkleton 9mo ago
    In the context of the kernel, it’s hard to say when that’s true. It’s very easy to fix some bug that resulted in a kernel crash without considering that it could possibly be part of some complex exploit chain. Basically any bug could be considered a security bug.
    - SSLy 9mo ago
      plainly, crash = DoS = security issue = CVE. QED.
      - deleted 9mo ago
        [deleted]
      - michaelt 9mo ago
        BRB, raising a CVE complaining the OOM killer exists.
        pamcake 9mo ago
        Memory leaks are usually (accurately) treated as DoS. OoM killer is a mitigation to contain them and not DoS the entire OS.
        worthless-trash 9mo ago
        I could be wrong. But operation by design isn't considered a bug.
        samus 9mo ago
        It is if some other condition is violated that is more important. Then the design might have to be reconsidered.
        suspended_state 9mo ago
        If it is faulty, then it's not a bug, it's a flaw.
        lfllfkddl 9mo ago
        It is possible to design a security vulnerability.
        worthless-trash 9mo ago
        Oh, now that is an exciting area.
- JCattheATM 9mo ago
  > From their perspective, on their project, with the constraints they operate under, bugs are just bugs. That's a pretty poor justification. Their perspective is wrong, and their constraints don't prevent them from treating security bugs differently as they should.
  - ada0000 9mo ago
    > almost any bugfix at the level of an operating system kernel can be a “security issue” given the issues involved (memory leaks, denial of service, information leaks, etc.) On the level of the Linux kernel, this does seem convincing. There is no shared user space on Linux where you know how each component will react/recover in the face of unexpected kernel behaviour, and no SKUs targeting specific use cases in which e.g. a denial of service might be a worse issue than on desktop. I guess CVEs provide some of this classification, but they seem to cause drama amongst kernel people.
  - samus 9mo ago
    You have a pretty strongly worded stance, but you don't provide an argument for it. May I suggest you detail why exactly you think their perspective is wrong, apart from "a lot of problems in the past could have been avoided"?
    - JCattheATM 9mo ago
      My view here isn't uncommon, even if it's a minority view. I've noticed a lot of people tend to just defend and adopt the stances of projects they like or use without necessarily thinking things through, and I assume that's at least partly the case here. There's been a lot of criticism written on the kernel devs stance over the last, what, 20 years? One obvious problem is that without giving security bugs, i.e. vulnerabilities priority, systems stay vulnerable until the bug gets patched at whatever place in the queue it happens to be at.
beanjuiceII 9mo ago
did you read it? because that's not their view at all
firesteelrain 9mo ago
“A bug is a bug” is about communication and prioritization, not ignoring security. Greg’s post spells that out pretty clearly.
- JCattheATM 9mo ago
  Yes, that's what I was criticizing....
akerl_ 9mo ago
This feels almost too obvious to be worth saying, but “the rest of the industry” does not in fact have a uniform shared stance on this.
jacobsenscott 9mo ago
Classifying bugs as security bugs is just theater - and any company or organization that tries to classify bugs that way is immature and hasn't put any thought into it. First of all "security" is undefined. Second, nearly every bug can be be exploited in a malicious way, but that way is usually not easy to find. So should every bug be classified as a security bug? Or should only bugs where a person can think of a way on the spot during triage to exploit that bug as a security bug? In that case only a small subset of your "security" bugs are classified as such. It is meaningless in all cases.
- JCattheATM 9mo ago
  > First of all "security" is undefined. Nonsense.
- therealrootuser 9mo ago
  > nearly every bug can be be exploited in a malicious way This is a bit contextually dependent. "This widget is the wrong color" is probably not a security issue in most cases, unless the widget happens to be a traffic signal, in which case it is a major safety concern. Even the line between "this is a bug" and "this is just a missing, incomplete, or poorly thought out feature" can get a bit blurry. At a certain point, many engineers get frustrated trying to pick apart the difference between all these ways of classifying the code they are writing and just want to get on with making the system work better.
- ykonstant 9mo ago
  > "security" Security is not a dirty word, Blackadder.
- staticassertion 9mo ago
  > First of all "security" is undefined. No it isn't. Security boundaries exist and are explicit. It isn't undefined at all. Going from user X to user Y without permission to do so is an explicit vulnerability. The kernel has permissions boundaries. They are explicit. It is defined. > Second, nearly every bug can be be exploited in a malicious way, No they can't.
themafia 9mo ago
> a lot of problems in the past could have bee avoided Such as?
schmuckonwheels 9mo ago
Linus has been very clear on avoiding the opposite, which is the OpenBSD situation: they obsess about security so much that nothing else matters to them, which is how you end up with a mature 30 year old OS that still has a dogshit unreliable filesystem in 2026. To paraphrase LT, security bugs are important, but so are all the other bugs.
- JCattheATM 9mo ago
  OpenBSD doesn't really stress about security so much as they made that their identity and marketing campaign - their OS is lacking too many basic capabilities a security focused OS should have. > To paraphrase LT, security bugs are important, but so are all the other bugs. Right, this is wrong, and that's the problem. Security bugs as a class are always going to be more important than certain other classes of bugs.
  - cedws 9mo ago
    And their ‘no remote holes’ is true for a base install with no packages, not necessarily a full system. I think the OpenBSD approach of secure coding is outdated. The goal should have always been to take human error out of the equation as much as possible. Rust and other modern memory safe languages move things in that direction, you don’t need ultra strict coding standards and a bible of compiler flags.
    - JCattheATM 9mo ago
      > I think the OpenBSD approach of secure coding is outdated. I don't think it's outdated it's a core part of the puzzle. The problem with their approach is they rely on it 100%, and have not enough in place (and yes, I'm aware of all the mitigations they do have) to protect against bugs they miss. This is a lot less true now than it was 15 - 20 years ago, but it's still not great IMO.
  - 6r17 9mo ago
    I have to disagree it's worst than you think ; open-bsd has so many mitigation in place that your computer will probably run 50% slower than a traditional OS. In reality you do not want to be playing 100% safety everywhere because this is simply expensive. You might prefer to create an isolated network on which you can set up un-mitigated servers - those will be able to run at 100% capacity. This can be looked upon when compiling the linux kernel, the mitigation options are rather numerous - and you'll have to also pick a sleep time ; what i'm saying is - currently linux only allows you to tune a machine to a specific requirement - it's not a spaceship on which you can change the sleep time frequency; dynamically shutdown mitigation ; and imagine that you are performing - In the same spirit, if you are holding keys on anything else than open-bsd ; I hope for you that you have properly looked up what you were installing.
redleader55 9mo ago
The rest of the industry relies on following a CVE list and ticking off vulnerabilities as a way to ensure "owners" are correctly assigned risk and sign it off - because there is nothing else that "owners" could do. The whole security through CVE is broken and is designed to be useful to create large "security organizations" that have the single purpose of annoying everyone with reports without solving any issues.
deleted 9mo ago
[deleted]

DebugDruid 9mo ago

Sometimes I dream about a 100% secure OS. Maybe formal verification is the key, or Rust, I don’t know. But I would love to know that I can't be hacked.

jeffbee 9mo ago
The problem is that for the overwhelming majority of use cases the isolation features that are violated by security bugs are not being used for real isolation, but for manageability and convenience. Virtualization, physical host segregation, etc are used to achieve greater isolation. People don't necessarily care about these flaws because they aren't actually exposed to the worst case preconditions. So the amount of contributor attention you could get behind a "100% secure OS" might not be as large as you are hoping. Anyway if you want to work on such things there are various OS development efforts floating around.
- nine_k 9mo ago
  Isolation is one thing, correctness is another. You may have architecturally perfect, hardware-assisted isolation, but triggering a bug would breach it. This is how a typical break out of a VM, or a container, or a privilege escalation, happens. There is a difference between a provably secure-by-design system, and a formally proven secure implementation, like Sel4.
- ameliaquining 9mo ago
  Obligatory https://xkcd.com/2044/ https://xkcd.com/2044/.
themafia 9mo ago
> But I would love to know that I can't be hacked. Cool. So social engineering it is. You are your own worst enemy anyways.
- staticassertion 9mo ago
  A world in which the only way to get hacked is to be tricked would be an insane improvement over today. There are a lot of ways to solve social engineering issue with tech solutions too - FIDO2 is one example, as would be app isolation, etc.

ryanisnan 9mo ago

[flagged]

cogman10 9mo ago
Why? What benefit would https provide over http when visiting a pure information (and I'm guessing statically generated) website?
- fordsmith 9mo ago
  If you are on a public network without using a VPN you open yourself up to MITM to inject something malicious
  - cogman10 9mo ago
    Sure, but that's ultimately a pretty unlikely attack vector. An attacker still needs to exploit some unknown vulnerability of your web browser in order to get something malicious going. I basically expect that sort of attack to only be pulled off by a state actor or by a black hat convention for the lolz.
    - nine_k 9mo ago
      ISPs used to inject ads into HTTP-served pages as recently as 10 years ago, I personally remember that. Not only tiny ISPs. I'm not alone: https://superuser.com/questions/902635/isp-is-inserting-ads-into-web-pages https://superuser.com/questions/902635/isp-is-inserting-ads-... Ads injection is a relatively benign kind of tampering. It could be much more creative and sinister.
    - deleted 9mo ago
      [deleted]
- bqmjjx0kac 9mo ago
  Confidentiality, integrity, and authenticity :)

miduil 9mo ago

> If you are forced to use encryption to report security problems, please reconsider this policy as it feels counterproductive (UK government, this means you…) LOL

vlovich123 9mo ago

I think the most practical reason not to flag which bugs are security bugs is to avoid helping blackhat hackers by painting a giant neon sign and that should be more than enough. I think all the other explanations are just double-think. Why? If "bugs are just bugs" is really a true sentiment, why is there a separate disclosure process for security bugs? What does it even mean to classify a bug as a security bug during reporting if it's no different than any other bug report? Why are fixes developed in secret & potential embargoes sometimes invoked? I guess some bugs are more equal than others?

fguerraz 9mo ago
As mentioned in the article, every bug is potentially a security problem to someone. If you know that something is a security issue to your organization, you definitely don't want to paint a target on your back by reporting the bug publicly with an email address <your_name>@<your_org>.com. In the end, it is really actually quite rare (given the size of the code base and the popularity of linux) that a bug has a very wide security impact. The vast majority of security issues don't affect organizations that are serious about security (yes really, SELinux eliminates or seriously reduces the impact of the vast majority of security bugs).
- vlovich123 9mo ago
  The problem with that argument is that the reports don’t necessarily come from the organization for whom it’s an issue. Security researchers unaffiliated not impacted by any such issue still report it this way (eg Project Zero reporting issues that don’t impact Google at all). Also Android uses SELinux and still has lots of kernel exploits. Believing SELinux solves the vast majority of security issues is fallacious, especially since it’s primarily about securing userspace, not the kernel itself .
  - suspended_state 9mo ago
    > The problem with that argument is that the reports don’t necessarily come from the organization for whom it’s an issue. You can already say that for the majority of the bugs being fixed, and I think that's one of the points: tagging certain bugs as exploitable make it seem like the others aren't. More generally, someone's minor issue might be a major one for someone else, and not just in security. It could be anything the user cares about, data, hardware, energy, time. Perhaps the real problem is that security is just a view on the bigger picture. Security is important, I'm not saying the opposite, but if it's only an aspect of development, why focus on it in the development logs? Shouldn't it be instead discussed on its own, in separate documents, mailing lists, etc by those who are primarily concerned by it?

badgersnake 9mo ago

And then all our customers will demand fixes for them in our docker images, because they’re that smart. There must be a way to ship a docker image without a kernel, since it doesn’t get used for anything anyway.

derkades 9mo ago
Huh, how do you unintentionally ship a Linux kernel in a container image? The common base images definitely don't contain the kernel.
- staticassertion 9mo ago
  The only thing I can imagine is that they've somehow managed to rely on kernel headers in their image? idk
  - deleted 9mo ago
    [deleted]
shepherdjerred 9mo ago
https://github.com/wolfi-dev https://github.com/wolfi-dev

coppsilgold 9mo ago

Recently, things have been advancing which may finally allow a seamless virtualization experience on the Linux desktop (and match QubesOS in some security aspects). GPU drivers supporting native contexts with Mesa support. Wayland sharing between guest and host. It used to be somewhat sloppy (involved protocol parsing; sommilier & wayland-proxy-virtwl) but recently someone undertook a project to do it properly that may soon bear fruit: https://codeberg.org/drakulix/wl-cross-domain-proxy https://codeberg.org/drakulix/wl-cross-domain-proxy A VMM to utilize these features: https://github.com/AsahiLinux/muvm https://github.com/AsahiLinux/muvm And a solution which ties these things together: https://git.clan.lol/clan/munix https://git.clan.lol/clan/munix

conradev 9mo ago
This is really cool! I wonder if it would be possible to live-migrate apps from one machine running munix to another. You could pause, transfer, and resume the virtual machine.

_zagj 9mo ago

Meanwhile it's 2026 and Greg's own website still doesn't support TLS.

juliangmp 9mo ago
Honestly, until encrypted client hello has widespread support, why bother? I mean I did it for fun the first time and now with caddy its not a lot of effort. But for a personal blog, a completely static site, what benefit do you get from the encryption? Anyone monitoring the traffic will see the domain in clear text anyway. And they'd see the destination IP, which I imagine in this case being one server that has exactly one domain pointed at it.
- swinglock 9mo ago
  Men in the middle including predatory ISPs can not only spy but also enrich. Injecting JavaScript and embedding ads is the best case scenario. You don't want that. In addition even without bad actors TLS will prevent random corruption due to flaky infrastructure from breaking the page and even caching those broken assets, preventing a reload from fixing it. TCP/IP alone doesn't sufficiently prevent this.
  - psnehanshu 9mo ago
    TCP ensures what gets sent on one side gets received on the other side. TLS just encrypts the data. So even without TLS, random corruptions won't happen unless someone does MITM attack.
    - swinglock 9mo ago
      No it does not. I've had this happen in legacy systems myself. The checksums of TCP/IP are weak and will let random errors through to L7 if there are enough of them. It's not even CRC and you must bring your own verification if it's critical for your application that the data is correct. TLS does that and more, protecting not only against random corruption but also active attackers. The checks you get for free are to be seen only as an optimization, letting most but not all errors be discarded quick and easy. Just use TLS.

tuananh 9mo ago

this is why redhat is still relevant in 2025. there's always a need for this kind of work.

staticassertion 9mo ago
I think you could make a stronger case for the opposite. How does Redhat know which commits to cherry when upstream explicitly won't tell you which are relevant to security?
- invokestatic 9mo ago
  Because Red Hat pays the salaries of dozens (hundreds?) of kernel maintainers all over different subsystems. So they’re subject matter experts, and know exactly which ones are relevant to Red Hat.
  - thrwwy81faa457 9mo ago
    This is the right answer. Source: 10+y long (past) tenure at RH in a team adjacent to the kernel team. EDIT: also because companies like RH tend to know, and are happy to know, the details of their customers' deployments. Compare the article: > Always remember, kernel developers: > - do not know your use case. > - do not know what code you use. > - do not want to know any of this.
    - staticassertion 9mo ago
      https://bugzilla.redhat.com/show_bug.cgi?id=1708775 https://bugzilla.redhat.com/show_bug.cgi?id=1708775 https://www.openwall.com/lists/oss-security/2020/06/23/2 https://www.openwall.com/lists/oss-security/2020/06/23/2 Even RHEL misses things that don't get announced. This is a big issue for LTS kernels and downstreams, although RHEL does a much better job than most due to the nature of the company/ products. I don't have tons of examples off hand but Spender and Project Zero have a number of examples like this (not necessarily for RHEL! Just in general where lack of CVE led to downstreams not being patched). https://googleprojectzero.github.io/0days-in-the-wild/0day-RCAs/2021/CVE-2021-1048.html https://googleprojectzero.github.io/0days-in-the-wild/0day-R... Who is helped by this, for example? https://x.com/grsecurity/status/1486795432202276864 https://x.com/grsecurity/status/1486795432202276864 > Always remember, kernel developers: > - do not know your use case. > - do not know what code you use. > - do not want to know any of this. I just found this part so odd. You don't need to know how users are deploying code to know that a type confusion in an unprivileged system call that leads to full control over the kernel is a vulnerability. If someone has a very strange deployment where that isn't the case, okay, they can choose not to patch. It's odd for every distro to have to think "is this patch for a vulnerability?" with no insight from upstream on the matter. Thankfully, researchers can go out of their way to get a CVE assigned.

tuananh 9mo ago

if they really think that, they should have remove their CNA, no?

theamk 9mo ago
Nah, "removing CNA" = "let any security researcher decide what kernel vulnerability is" And unfortunately, there are plenty of security researchers who are only interested in personal CVE counts, and will try to assign highest priority to a mostly harmless bug.
- tuananh 9mo ago
  but keeping the CNA and decide, "nah, i wont number it" instead?
  - theamk 9mo ago
    They do number it.. in fact once they become CNA in 2024, the amount of kernel CVE's has increased almost 10x (see [0]) They just stopped assigning priorities/impact scores to them, because "A simple bugfix for a minor thing for one user could be a major system vulnerability fix for a different user, all depending on how Linux is being used" (For an example of why having severity rating on CVE is a bad idea, see Redhat's treatment of CVE-2025-68343[1] - they gave "high", score 7. Many security teams in large corps would require a quick patch/kernel upgrade. And yes, this is a null-pointer dereference in a single USB device driver. Even if this is exploitable (which I am not sure about), this driver is _never_ going to be loaded into any our cloud machines, so most of our infra is not affected). [0] https://www.cvedetails.com/product/47/Linux-Linux-Kernel.html?vendor_id=33 https://www.cvedetails.com/product/47/Linux-Linux-Kernel.htm... [1] https://access.redhat.com/security/cve/cve-2025-68343 https://access.redhat.com/security/cve/cve-2025-68343

staticassertion 9mo ago

"A bug is a bug" lol. There's a massive difference between "DoS requiring root" and "I can own you from an unprivileged user with one system call". You can say "but that DoS could have been a privesc! We don't know!" but no one is arguing otherwise? The point is that we do know the impact of some bugs is strictly a superset of other bugs, and when those bugs give control or allow a violation of a defined security boundary, those are security bugs. This has all been explained to Greg for decades, nothing will change so it's just best to accept the state - I'm glad it's been documented clearly. Know this - your kernel is not patched unless you run the absolute latest version. CVEs are discouraged, vuln fixes are obfuscated, and you should operate under that knowledge. Attackers know how to watch the commit log for these hidden fixes btw, it's not that hard. edit: Years later and I'm still rate limited so I can't reply. @dang can this be fixed? I was rate limited for posting about Go like... years ago. To the person who replies to me: > This is correct for a lot of different software, probably most of it. Why is this a point that needs to be made? That's not true at all. You can know if you're patched for any software that discloses vulnerabilities by checking if your release is up to date. That is not true of Linux, by policy, hence this entire post by Greg and the talks he's given about suggesting you run rolling releases. Sorry but it's too annoying to reply further with this rate limiting, so I'll be unable to defend my points.

tamirzb 9mo ago
> Know this - your kernel is not patched unless you run the absolute latest version. This is correct for a lot of different software, probably most of it. Why is this a point that needs to be made?
- thrwwy81faa457 9mo ago
  (Parent has already replied by editing their original comment, but I'll tack on a bit more info, from my perspective.) The reason this has to be emphasized is that all new code runs the risk of regressions, and in a production environment, you hate regressions. Therefore, not only do you not want new features, but you also don't want irrelevant bug fixes. Bug fixes, even security fixes, are not magically free of independent regressions. Therefore a valid incentive exists to minimize backports to production environments. And such a balancing act depends on the careful investigation of the impact of known bugs, one by one. From the fine blog post: > For those that are always worried “what if a bugfix causes problems”, they should remember that a fix for a known bug is better than the potential of a fix causing a future problem as future problems, when found, will be fixed then. A whole lot of users can disagree with this. For good, practical reasons. The expected damage of a known bug may be estimated, while an unknown regression brought in by the fix for the known bug may cause way worse damage.

bschmidt25011 9mo ago

[dead]