Goodix Parcel patch for Android Q

The problem

"Parcel object increased from 104 to 120 bytes, and many functions in both libraries had two Parcel objects next to each other in their stack.

Each of those functions had their stack modified to be increased by 32 bytes to accommodate for the increased Parcel object size. The stack pointer offsets for the 2nd Parcel, along with any other items in the stack after the Parcels (which was just the stack canary), were also adjusted to accomodate for the change in Parcel size."

Source: https://github.com/jabashque/proprietary_vendor_leeco/commit/652378f8839f2851a65334a0c659d7ba06fd29cc (@jabashque)

The solution

This repository presents a script which automates the patching process

Tutorial

1. Ghidra work

   a. Download Ghidra here b. Create a new project and import all the goodix libraries (those should be in the WORKING folder) c. Analyze all the files d. Export as "C/C++" in DATA/filename.c (ex: DATA/libfp_client.c) e. Run the following command for each file

   grep -B10 "Parcel aPStack" DATA/filename.c | grep "//" > DATA/filename_f

   (/!\ This step may return lines with "Warning" in, please remove it and do this step manually)

2. objdump

   a. Install AARCH64 toolchain

   sudo apt-get install binutils-aarch64-linux-gnu

   b. Disassemble every file

   aarch64-linux-android-objdump -d WORKING/filename.so > DATA/filename.asm

3. Execute the script

   a. Install Python 3 depedencies

   pip3 install -r requierments.txt

   b. Replace config lines in script.py (the script must be executed file by file)

   asm_file = "DATA/filename.asm"
   functions_file = "DATA/filename_f"
   output_file = "WORKING/filename.so"

   c. Execute the script (/!\ This will overwrite WORKING/filename.so)