The researchers pointed out that the vulnerability cannot be exploited remotely. An attacker can trigger the issue by providing crafted inputs to applications that employ these [syslog] logging functions [in apps that allow the user to feed crafted data to those functions].
According to the link in the article, the qsort() bug can only be triggered with a non-transitive cmp() function. Would such a cmp function ever be useful?
You don't necessarily have to write a non-transitive cmp() function willingly, it may happen that you write one without realizing due to some edge cases where it's not transitive.
Security-critical C and memory safety bugs. Name a more iconic duo...
I'd have kinda preferred for public disclosure to have happened after the fix propagated to distros. Now we get to hurry the patch to end-users which isn't always easily possible. Could we at least have a coordinated disclosure time each month? That'd be great.
They did follow that. You can read their disclosure timeline in their report.
Problem is that the devs of glibc aren't the only people interested in getting glibc patched but us distro maintainers too.
What I would have preferred would be an early private disclosure to the upstream maintainers and then a public but intentionally unspecific disclosure with just the severity to give us distro people some time to prepare a swift rollout when the full disclosure happens and the patch becomes public.
Alternatively, what would be even better would have been to actually ship the patch in a release but not disclose its severity (or even try to hide it by making it seem like a refactor or non-security relevant bugfix) until a week or two later; ensuring that any half-decent distro release process and user upgrade cycle will have the patch before its severity is disclosed. That's how the Linux kernel does it AFAIK and it's the most reasonable approach I've seen.
glibc is great, but holy shit the source code is obscured into oblivion, so hard to understand, with hardcoded optimizations, and compiler optimizations. I understand how difficult is to find vulnerabilities. A bit sad that the only C lib truely free software is so hard to actually read its code or even contribute to it.
For what it's worth, glibc is very much performance-critical, so this shouldn't be a surprise. Any possible optimization is worth it.
There are a ton of free software libc implementations outside of glibc. I think most implementations of libc are free software at this point. There's Bionic, the BSD libcs, musl, the Haiku libc, the OpenSolaris/OpenIndiana libc, Newlib, relibc, the ToaruOS libc, the SerenityOS libc and a bunch more. Pretty sure Wine/ReactOS also have free implementations of the Windows libc.
Glibc has extensions that fragment compatibility. If Glibc is replaced by another libc, some apps prints an error, or don't work. I noticed that on Alpine.
Unlikely, unless you drop backwards compatibility for undefined behaviour. Unless you write a complete specification on it, you'll end up either breaking old stuff, or slowly rebuilding the same problems.
The vulnerability is in the library's logging function, which is coded in the C language. musl is also C (afaik), it's just a more modern, safer rewrite of libc.
I'm not sure what you mean by a "vulnerability in the logs". In a logger or parser, sure, but did you think text data at rest was able to reach out and attack your system?
Void offers musl too. Unless they've discontinued it.
But
compile everything yourself?
I do (almost) exactly that. I run Gentoo almost everywhere.
The 'almost' is because Gentoo now offers an official bin repository too, so I can mix compiled and pre-compiled software. (Although you've always had the option to set up your own binary host).
I replied to another comment with this, but Debian 12(stable, bookworm) and 13(testing, trixie) are affected by this but 12(stable, bookworm) has a patch out in the security repo.
If you wanna know wether or not you’re affected,
apt list libc
will show your version and the one you want is 2.36-9+deb12u4
If you don’t have that,
apt update && apt upgrade
will straighten you out
13(testing, trixie) has 2.37, but it’s not fixed yet.
I'd just like to interject for a moment. What you call "GNU Library C" is actually GNU with Linux library C and some C++ for those nifty templates, or as we like to call it "GNU/Linux Library C/C++". Which, to be honest, it's more like "GNU/Linux Library C/C-with-Classes" the way they're teaching it at school, oh well.