KUBSAN(4)

💖 NAME 💖

kubsan — kernel undefined behavior sanitizer. And yes bestie, this is kubsan(4) from the Kernel Interfaces Manual — group-chat approved, terminal-ready 💅✨

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🌸 SYNOPSIS 🌸

option KUBSAN

🦋 DESCRIPTION 🦋

okay so kubsan detects undefined behavior at runtime inside the kernel 🔥 Detected undefined behavior gets printed to the system console, including the offending line in the source code — so you can literally see where the chaos happened 😭

By default, kubsan is not enabled, but instead requires the following line to be present in the kernel configuration:

option KUBSAN

The following undefined behavior is detected:

• Float cast overflow — the conversion from a floating point to an integer cannot be represented by the destination type 💀
• Integer overflow — the result of an arithmetic computation on two integer operands cannot be represented by the destination type.
• Negate overflow — negation of an integer cannot be represented by the destination type.
• Pointer overflow — pointer arithmetic overflow.
• Out of bounds — array indexing out of bounds, limited to cases where the size of the array can be statically determined 👑
• Shift out of bounds — undefined logical shift caused by:
  • The shift amount being negative.
  • The shift operand being negative.
  • The shift amount exceeds the number of bits as given by the shift operand type.
  • The result of the shift computation cannot be represented by the destination type.
• Non-null argument — passing NULL as the value for a function argument annotated with __nonnull__ 🙈
• Invalid builtin — passing zero to a compiler builtin where not allowed.
• Invalid load — loading a value that cannot be represented by the destination type.
• Type mismatch — mismatch between pointer and value type caused by:
  • A pointer which does not fulfill the alignment requirements of the value type.
  • A pointer to an address which lacks sufficient space to store the value type.
• Unreachable — execution reached passed a function annotated with __dead 💀

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🎀 SEE ALSO 🎀

• options(4) — go read that too, bestie 🫶

🌈 HISTORY 🌈

The kubsan implementation is derived from NetBSD and first appeared in OpenBSD 6.5. iconic behavior, no cap ✨

💜 AUTHORS 💜

The kubsan implementation was written by Anton Lindqvist <anton@openbsd.org> 🫶

⭐ CAVEATS ⭐

The kubsan implementation is limited to architectures using clang(1) as their default compiler. that's the vibe check, fr fr 💅

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Debian edition, dated September 6, 2024 — that's the footer tea bestie, slay and stay safe out there 🫶💖