is_kfence_address(9)

📦 version 7.3.1, in nixpkgs unstable

✨ is_kfence_address(9) ✨

ok so picture this: you're deep in the Kernel API Manual, section 9, and you find this little gem 💖 bestie, let me tell you about is_kfence_address — she's a tiny function with main character energy and she's here to save your heap from itself 🫶

🌸 NAME 🌸

is_kfence_address — check if an address belongs to the KFENCE pool 💅

🎀 SYNOPSIS 🎀

bool is_kfence_address (const void *addr );

like, yes, that's the whole thing. she's short. she's efficient. she's iconic ⭐

🦋 ARGUMENTS 🦋

  • addr — the address you want to check, bestie. that's it. that's the argument. no cap 🔥

🌈 RETURN 🌈

returns true or false, depending on whether the address is within the KFENCE object range ✨

literally just a vibe check for addresses. is she in the KFENCE zone or not? 💀

💜 DESCRIPTION 💜

okay so here's the tea, and it's important tea 🍓

KFENCE objects live in a separate page range and are not to be intermixed with regular heap objects. like, ever. (for example, KFENCE objects must never be added to the allocator freelists — not me stressing about this 😭).

if you fail to do that, it may and will result in heap corruptions. not "might". not "could". will. so yeah, is_kfence_address must be used to check whether an object requires specific handling 🔥 this is not optional, bestie, this is the whole point 👑

fr fr, this one is a correctness thing. treat her with respect 🙈

🧚 NOTE 🧚

this function may be used in fast-paths and is performance critical 👑

so future changes should take that into account. for instance, we want to avoid introducing another load, and therefore we need to keep KFENCE_POOL_SIZE a constant (until immediate patching support is added to the kernel) 💅

like, she's on the hot path. don't bloat her. periodt ✨

👑 SEE ALSO 👑

Kernel file ./include/linux/kfence.h:

the whole kfence friend group, honestly. go say hi 🫶🌈

and that's the page, bestie!! 💖 this one's from ./include/linux and dated October 2026 — so like, mark your calendars, she's from the future 🕰️✨ slay!! 🎀💜

📦 where this page comes from