Skip to content
  • Home Home Home, current page.
  • Moments Moments Moments, current page.

Saved searches

  • Remove
  • In this conversation
    Verified accountProtected Tweets @
Suggested users
  • Verified accountProtected Tweets @
  • Verified accountProtected Tweets @
  • Language: English
    • Bahasa Indonesia
    • Bahasa Melayu
    • Català
    • Čeština
    • Dansk
    • Deutsch
    • English UK
    • Español
    • Filipino
    • Français
    • Hrvatski
    • Italiano
    • Magyar
    • Nederlands
    • Norsk
    • Polski
    • Português
    • Română
    • Slovenčina
    • Suomi
    • Svenska
    • Tiếng Việt
    • Türkçe
    • Ελληνικά
    • Български език
    • Русский
    • Српски
    • Українська мова
    • עִבְרִית
    • العربية
    • فارسی
    • मराठी
    • हिन्दी
    • বাংলা
    • ગુજરાતી
    • தமிழ்
    • ಕನ್ನಡ
    • ภาษาไทย
    • 한국어
    • 日本語
    • 简体中文
    • 繁體中文
  • Have an account? Log in
    Have an account?
    · Forgot password?

    New to Twitter?
    Sign up
RichFelker's profile
Rich Felker
Rich Felker
Rich Felker
@RichFelker

Tweets

Rich Felker

@RichFelker

Yeah, I do @musllibc, FOSS & infosec stuff. But now is not the time for a mostly-/only-tech Twitter feed.

musl-libc.org
Joined March 2014

Tweets

  • © 2018 Twitter
  • About
  • Help Center
  • Terms
  • Privacy policy
  • Cookies
  • Ads info
Dismiss
Previous
Next

Go to a person's profile

Saved searches

  • Remove
  • In this conversation
    Verified accountProtected Tweets @
Suggested users
  • Verified accountProtected Tweets @
  • Verified accountProtected Tweets @

Promote this Tweet

Block

  • Tweet with a location

    You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more

    Your lists

    Create a new list


    Under 100 characters, optional

    Privacy

    Copy link to Tweet

    Embed this Tweet

    Embed this Video

    Add this Tweet to your website by copying the code below. Learn more

    Add this video to your website by copying the code below. Learn more

    Hmm, there was a problem reaching the server.

    By embedding Twitter content in your website or app, you are agreeing to the Twitter Developer Agreement and Developer Policy.

    Preview

    Why you're seeing this ad

    Log in to Twitter

    · Forgot password?
    Don't have an account? Sign up »

    Sign up for Twitter

    Not on Twitter? Sign up, tune into the things you care about, and get updates as they happen.

    Sign up
    Have an account? Log in »

    Two-way (sending and receiving) short codes:

    Country Code For customers of
    United States 40404 (any)
    Canada 21212 (any)
    United Kingdom 86444 Vodafone, Orange, 3, O2
    Brazil 40404 Nextel, TIM
    Haiti 40404 Digicel, Voila
    Ireland 51210 Vodafone, O2
    India 53000 Bharti Airtel, Videocon, Reliance
    Indonesia 89887 AXIS, 3, Telkomsel, Indosat, XL Axiata
    Italy 4880804 Wind
    3424486444 Vodafone
    » See SMS short codes for other countries

    Confirmation

     

    Welcome home!

    This timeline is where you’ll spend most of your time, getting instant updates about what matters to you.

    Tweets not working for you?

    Hover over the profile pic and click the Following button to unfollow any account.

    Say a lot with a little

    When you see a Tweet you love, tap the heart — it lets the person who wrote it know you shared the love.

    Spread the word

    The fastest way to share someone else’s Tweet with your followers is with a Retweet. Tap the icon to send it instantly.

    Join the conversation

    Add your thoughts about any Tweet with a Reply. Find a topic you’re passionate about, and jump right in.

    Learn the latest

    Get instant insight into what people are talking about now.

    Get more of what you love

    Follow more accounts to get instant updates about topics you care about.

    Find what's happening

    See the latest conversations about any topic instantly.

    Never miss a Moment

    Catch up instantly on the best stories happening as they unfold.

    1. Jean Yang‏ @jeanqasaur Sep 26

      Jean Yang Retweeted Jonathan Levine

      It's always amazing to me that abstractions are so fragile in practice we still haven't managed to fully abstract over numbers.https://twitter.com/JonMLevine/status/1044950721857298432 …

      Jean Yang added,

      Jonathan Levine @JonMLevine
      .@qualys “discovered an integer overflow in [@RedHat] Linux kernel's create_elf_tables() function: on a 64-bit system, a local attacker can exploit this vulnerability via a SUID-root binary and obtain full root privileges,” keep an eye on RHEL and CentOS http://j.mp/2xTDuj9 
      3 replies 6 retweets 38 likes
    2. Steve Canon‏ @stephentyrone Sep 26
      Replying to @jeanqasaur

      Depends on what you mean by “numbers”. We’ve had pretty good abstractions for integers for half a century, we don’t use them because ZOMGFAST. Reals are hopeless, of course.

      2 replies 0 retweets 2 likes
    3. John Regehr‏ @johnregehr Sep 26
      Replying to @stephentyrone @jeanqasaur

      I would not say that there exists a good integer abstraction that also generally works in the low-level parts of an OS kernel

      3 replies 0 retweets 3 likes
    4. Rich Felker‏ @RichFelker Sep 26
      Replying to @johnregehr @stephentyrone @jeanqasaur

      Sure there is. Static arbitrary precision where inability to determine static bound is a compile time error.

      1 reply 0 retweets 2 likes
    5. Steve Canon‏ @stephentyrone Sep 26
      Replying to @RichFelker @johnregehr @jeanqasaur

      See, Rich is the absolutist. I’m the pragmatic one who will allow you a runtime error handler =)

      1 reply 0 retweets 4 likes
      Rich Felker‏ @RichFelker Sep 26
      Replying to @stephentyrone @johnregehr @jeanqasaur

      Nobody writes runtime handlers that do anything except BUG_ON();

      7:48 AM - 26 Sep 2018
      • 2 Likes
      • John Regehr George Brown
      1 reply 0 retweets 2 likes
        1. New conversation
        2. Rich Felker‏ @RichFelker Sep 26
          Replying to @RichFelker @stephentyrone and

          In any case, a runtime check is only meaningful with runtime sizing, meaning your language model has allocation going on under the hood, which means it's not suitable for low level programming of any sort.

          2 replies 0 retweets 0 likes
        3. Steve Canon‏ @stephentyrone Sep 26
          Replying to @RichFelker @johnregehr @jeanqasaur

          No, a runtime check is useful even without runtime sizing. I may have a computation on i64s that I believe cannot overflow, but I can't prove it to Z3's satisfaction--I'm offering a pragmatic option of "I don't think this will ever happen, but if it does, error out of the \

          2 replies 0 retweets 1 like
        4. Rich Felker‏ @RichFelker Sep 26
          Replying to @stephentyrone @johnregehr @jeanqasaur

          This is equivalent. Just add if (x>K) return error; (or assert) before the arithmetic. No need to put runtime check in the language's def of arithmetic.

          1 reply 0 retweets 0 likes
        5. Steve Canon‏ @stephentyrone Sep 26
          Replying to @RichFelker @johnregehr @jeanqasaur

          It's sometimes non-trivial to propagate "no overflow" back to a bound on the inputs. Letting compiler insert `jo` for you is a useful model.

          1 reply 0 retweets 1 like
        6. Steve Canon‏ @stephentyrone Sep 26
          Replying to @stephentyrone @RichFelker and

          Better still when the compiler can insert it *only* where it can't prove that it's unnecessary, and give you that feedback.

          1 reply 0 retweets 1 like
        7. Rich Felker‏ @RichFelker Sep 26
          Replying to @stephentyrone @johnregehr @jeanqasaur

          In some cases it would generate slightly more optimal code, but it makes the language more complex and hard to use, I think.

          1 reply 0 retweets 0 likes
        8. Steve Canon‏ @stephentyrone Sep 26
          Replying to @RichFelker @johnregehr @jeanqasaur

          Depends. If your goal is "make this as efficient as you can, but more importantly make it correct", it's a pretty nice solution. If your goal is "I want extremely precise manual control over the instructions generated", then yeah, it's probably not what you want.

          2 replies 0 retweets 0 likes
        9. Rich Felker‏ @RichFelker Sep 26
          Replying to @stephentyrone @johnregehr @jeanqasaur

          The former seems like a correct characterization but the latter seems off-base. My intent is to require write-/compile-time intervention in the form of some condition that feeds into a proof of boundedness when a proof does not emerge in an automatable way.

          0 replies 0 retweets 0 likes
        10. End of conversation

      Loading seems to be taking a while.

      Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.

        Promoted Tweet

        false

        • © 2018 Twitter
        • About
        • Help Center
        • Terms
        • Privacy policy
        • Cookies
        • Ads info