DownUnderCTF 2022 just-in-kernel Writeup

just-in-kernel was a kernel exploitation problem in DownUnderCTF 2022, and had 11 solves by the end of the CTF. We were provided a kernel bzImage, an initramfs.cpio.gz file, a launch.sh script to launch the kernel in QEMU, and the following prompt:

A just-in-time compiler implemented completely within the kernel, wow! It's pretty limited in terms of functionality so it must be memory safe, right?