This bug was fix in https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3b0462726e7ef281c35a7a4ae33e93ee2bc9975b
This exploit works on most pre-patch kernels for:
- CentOS 8 kernels higher than linux-4.18.0-305.el8
- Debian 11 kernels higher than 5.10.0-8
- Fedora 31/32/33 kernels higher than 5.3.7-301.fc31
- Ubuntu 18/20 kernels higher than 5.4.0-84 and 5.11.0-37.41
Please feel free to send a PR to update README if you find it could work on other kernels.