1. Introduction In late April 2026, security researcher Taeyang Lee publicly disclosed a Linux kernel vulnerability assigned CVE-2026-31431 and gave it an ironic name: Copy Fail. The name captures the essence of the bug. In 2017, a kernel developer fixed an AF_ALG crypto-interface bug where AAD was not copied…
This article was originally a set of notes written while reading QEMU's PCI implementation. The structure is not meant to be a complete PCI specification. The goal is more practical: start from PCI address-space concepts, follow how QEMU creates PCI buses and devices, then trace how an MMIO…
How It Started I had a piece of user-space code that needed to run inside the kernel. The normal approach would be to recompile it through the kernel build system, but that means maintaining a Kbuild setup, and rewriting all the user-space idioms in the code is genuinely painful. That…
