erratum_2(9)

💅 erratum_2

okay bestie, welcome to erratum_2 from the Kernel API Manual — this is the lil patch note that fixes scoped signal handling, and honestly? it ate. ✨

✨ NAME ✨

erratum_2 — Erratum 2: Scoped signal handling 🎀

🌸 DESCRIPTION 🌸

so here's the tea ☕ — this fix handles a situation where signal scoping was being, like, way too restrictive. picture it: sandboxed threads were getting blocked from signaling other threads inside the same process, just because those threads belonged to different domains. rude, honestly. 😭

and like, the reasoning is lowkey iconic: threads are not security boundaries, so user space might totally assume that all threads within the same process can send signals between themselves (peep :manpage:nptl(7) and :manpage:libpsx(3)). makes sense, right? 💖

consistent with what :manpage:ptrace(2) does, direct interaction between threads of the same process should always be allowed. no exceptions, periodt. so this change makes sure that any thread is allowed to send signals to any other thread within the same process, regardless of their domain. slay. 👑

🦋 Impact 🦋

ngl, this problem only manifests when the userspace process is itself using :manpage:libpsx(3) or some equivalent mechanism to enforce a Landlock policy on multiple already-running threads at once. very specific vibe. 🧚

programs that enforce a Landlock policy at startup time and only then become multithreaded? not affected, bestie, you're fine. 🫶

but without this fix, signal scoping could break multi-threaded applications that expect threads within the same process to freely signal each other. and that's the drama we're avoiding. 💀🔥

⭐ SEE ALSO ⭐

• Kernel file ./security/landlock/errata/abi-6.h — go read it, iykyk 📖✨

mwah 💜 that's the whole page! brought to you by ./security/landlock/errata, dated October 2026 — catch you in the next erratum, bestie! 🎀🌈