CVE-2021-28663

A basic PoC leak for CVE-2021-28663 (Internal of the Android kernel backdoor vulnerability)

This is a basic PoC for CVE-2021-28663. A design flaw in Mali GPU Android Kernel Driver.

1. Create a GPU_VA and also mmap to it so we can get virtual addr for phys pages.
2. Create an alias for phy pages, but don't do mmap so gpu_mapping remains as 1
3. Change flags of GPU_VA to BASE_MEM_DONT_NEED. Mali will make them evictable
4. Since we have reg for aliased page, now we can mmap to it. This will give us RDONLY access from CPU

Example run: