CVEs-PoC/2021/CVE-2021-3444.md

### [CVE-2021-3444](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-3444)
![](https://img.shields.io/static/v1?label=Product&message=kernel&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=trunk%3C%205.12-rc1%20&color=brighgreen)
![](https://img.shields.io/static/v1?label=Vulnerability&message=CWE-681%3A%20Incorrect%20Conversion%20between%20Numeric%20Types&color=brighgreen)

### Description

The bpf verifier in the Linux kernel did not properly handle mod32 destination register truncation when the source register was known to be 0. A local attacker with the ability to load bpf programs could use this gain out-of-bounds reads in kernel memory leading to information disclosure (kernel memory), and possibly out-of-bounds writes that could potentially lead to code execution. This issue was addressed in the upstream kernel in commit 9b00f1b78809 ("bpf: Fix truncation handling for mod32 dst reg wrt zero") and in Linux stable kernels 5.11.2, 5.10.19, and 5.4.101.

### POC

#### Reference
- http://packetstormsecurity.com/files/162117/Kernel-Live-Patch-Security-Notice-LSN-0075-1.html
- http://packetstormsecurity.com/files/164950/Kernel-Live-Patch-Security-Notice-LSN-0082-1.html
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9b00f1b78809

#### Github
- https://github.com/ARPSyndicate/cvemon
- https://github.com/Wi1L-Y/News